What Are Word Elements
Words in the Esper' language are made up of "word elements" or vorter'oy which may be thought of simply as prefixes, word roots, suffixes, and word endings. Any of these may be further subdivided, but the distinctions become more and more vague as it becomes harder for a reader or listener to distinguish the which of these subcategories was intended by the writer or speaker for a particular part of a word. The only one of these which really has its own clear distinction is the word ending, which loses that clear distinction when the writer doesn't mark it with a preceding apostrophe or when the speaker doesn't mark it with by a drop in syllable stress or by preceding it with an increase in syllable stress.
Parts of Speech
First, a bit of clarification about the word "word" and just what constitutes such an entity in the Esper' language. The term is a bit vague, so when clarification is needed it may be best to specify "root word", which is a word root standing as a word in its own right, or "fully qualified word" to signify an exact form of particular word with all its attachments in place, or the "stem of a word" or "word stem" which signifies a word with all role endings removed or a word to which word elements are to be added. For example, kat'o is not a word stem because it has the substantive ending 'o attached marking its intended usage as that of a noun, and the word litotuk'o meaning literally "bed cloth" is composed of the word root tuk which describes a section of cloth or similar material, with the substantive ending, and the fully qualified word lit'o converted to a prefix to form a compound word, meaning a word with more than one root.
A "word root" is a word element which can stand on its own as a word. Unlike the English language, writing and speech in the Esper' language are meant to correspond to each other as directly as possible. In other words, people should be able to write as they speak and speak as they write. However, notice that there is a distinction between Esper' which is typed or carefully spoken or written, and Esper' which is spoken or hand written more casually and may stray farther from such ideals. This is perfectly acceptable, but should not be mistaken as model of clear communication in the Esper' language. Word elements which can not stand alone well as spoken words, should also not stand alone as written words.
While a particular word root may be readily recognized as a helping verb or a preposition or whatever, without the need to attach a role ending, and it is perfectly fine to use them that way, the role endings are meant to anchor the Esper' language so that its usage doesn't drift too quickly to be practical and to help people clarify in what way any particular Esper' word is meant to be taken within the given context.
While a single word may often be seen as having multiple meanings, in the Esper' language such meanings are from to blend with each other depending on the context in which the word is used, including any modifying or clarifying elements attached to the word in the worm in which it is encountered. so it is often best to think of such alternate meanings as past of a "range of meanings" for the given word and to recognize that if you know the range of meanings for a particular word to extend into areas which would be unacceptable as interpretations of what you are trying to say, it may be better to choose a different word or include specific clarification. For example, let's say you are getting some food served to you and you wish the amount given to be increased. If the person serving the food just added in a scoop of something, the concept "again" may enter your mind. One simple way to express that concept would with the root word re which you may also immediately recognize as a prefix used in English with a very similar range of meanings, but this could also be taken to mean "go back" which may result in just the opposite of what you wanted, so perhaps a better choice if you wish to avoid having to clarify further would be the root word pli meaning "more" as in to augment or increase.
It is quite easy in the Esper' language to use in a form which lacks explicit labeling of its intended "part of speech" role. This is normal in casual conversation and to a lesser extent even in carefully thought out communication, but one thing to keep in mind is that the Esper' language is intended to be easy for people from a wide variety of linguistic backgrounds to learn, and any assumptions about word order implying which word fills which role may be different for different people, so it is best to avoid stripping away these helpful word elements too much. For example, hi' frap' ci'' can be taken several different ways at least. The word roots hi and ci have masculinity and femininity respectively included in their basic definitions, and the word element frap may be readily recognized as carrying the meaning of "hit" or "strike" so one may take that to mean "he hit her" based on certain assumptions, but the assumptions made by another person may be different. True, hi and ci are obviously pronouns and not likely to have been meant as verbs, and a sentence generally does contain a verb, but was that in the past tense? Could it have been "he hits her" or "he will hit her" or perhaps even "he should hit her" or some other variation? Of course it could. And what about the pronouns themselves? Unlike their closest English counterparts, the Esper' proforms hi and ci do not carry in their definitions that they must be taken as "third person" so this could have meant "he hit me" or "I hit her" or if you are speaking to a man and a woman, one of them may take it to mean "the male should hit the female" or even "the female should hit the male" if that person is not making an assumption about word order that English many speakers are likely to take for granted as always safe to assume. You see, the subject of the verb does not have to come before the verb, and the direct object of the verb does not have to come after the verb. This lack of restriction on the word order is inherited from the Esperanto language where it was included to make the language easier for people to communicate who otherwise might make conflicting assumptions. Also inherited from the Esperanto language is a solution to the resulting ambiguity. In the Esperanto language, "he hit her", which was the first possible translation mentioned here, may be written as li frapis ŝin and those three words may be rearranged into any of the six possible orders without changing the basic meaning of the sentence. The same phrase, in the same order, can be written in Esper' as hi' frap'is ci'n or as li' frap'is ci'n depending on whether the Esperanto pronoun li was meant to be taken as masculine or gender ambiguous respectively, since in Esperanto the same word serves both roles. Again, the order of the three words may be rearranged without risk of changing the basic meaning in any significant way.
The Esperanto word ŝin and the Esper word ci'n are both feminine pronouns in the accusative case and can both be pronounced the same way. The accusative case specifies that the word is intended as the direct object of the verb, leaving the other pronoun to act as the subject by default. The Esper' language also allows you to explicitly declare the nominative, so besides being able to rearrange the words, you could also rewrite hi' frap'is ci'n as hi'z frap'is ci' which is equally clear about which pronoun is meant in which role, if the assumption is made that those two roles are likely to be represented. In other words, if it is assumed that one pronoun must be the subject of the verb and the other must be the direct object of the verb, then specifying either as the subject or either as the direct object leaves the other to fill the remaining assumed position, regardless of word order. Of course this is an extremely simple example and it's probably easier to make such assumptions in such a simple arrangement of merely three words. However, if you wish to provide your speakers or listeners with added clarity, it is possible to explicitly specify the accusative case explicitly on one pronoun and the nominative case on the other. It is also of course possible to leave off the general past tense ending 'is or to replace it with some other verb ending such as the active present used in hi'z frap'int ci'n meaning "he's hitting her" or even to throw one of the pronouns out and mark the other as both the subject and direct object of the verb as in hi'nz frap'u which can be roughly translated into "he should hit himself" and again retains the same basic meaning if the words are rearranged. This is not to say that word order is completely unimportant in the Esper' language, but through the use of explicit role marking it is possible to allow words to be arranged more freely and to do away with many assumptions about word order which may vary from one linguistic background to another.
Language as an Art
You may have noticed that some parts of speech are indicated by a prefix or suffix made into part of the word stem, while others are attached as a separate role ending. There is a linguistic science to this, but in actual usage it may tend to be more art than science. This is because the Esper' language is intended for human communication and each human is unique. Sure, it would have been possible to mark all parts of speech explicitly in arrangements which follow strict rules, and in fact the early versions of the Pont' language, which included Esper' from its inception, did exactly that before it was influenced by the Esperanto language. The Esper' language, in its present form, allows much more flexibility, and generally has at least two very different ways of expressing any given facet of thought, each with its own range of applications and linguistic effect. For example, the possessive pronoun "your" from the English language may be translated into the genitive Esperanto pronoun "via" which the Esper' language may be clearly marked as adjectival in the worm vi'a which includes this possessive meaning in its range along with any other meanings which may be attributed to such an adjective, or may be given the correlative possessive ending "es" to form vi'es which is a bit less ambiguous, or it may be given the matching suffix "es" indicating ownership, and the substantive ending "o" to form vies'o meaning "yours" which of course may optionally be further augmented to mark it clearly as meant in the accusative case, as grammatically singular, as belonging to a specific number of you, as the nominative case, or whatever else the writer or speaker intends to express.
One of the benefits of the Esper' language's flexibility when it comes to such things as explicit and implicit parts of speech or grammatical word order is that it allows for significant artistic freedom. For example, when attempting to product a rhyme at the end of a sentence for lyrics or poetry, you may place the noun after it's modifying adjective or the adjective after the noun it modifies, allowing more options to choose from than if two such words always had to come in the same order to be grammatically correct. Further, you can choose whether or not to mark the role of the last word in such a case based on what serves your intended purpose best rather than based on what the language dictates you must do. This feature is inherited from the Esperanto language, where it was included for exactly that reason, but has been generalized in the Esper' language to be allowed outside of song and poetry as well, and to be applicable to any word rather than only to nouns. Just keep in mind that the more information you provide, the better your chances of being more fully understood and the less likely you are to be misunderstood.
Sometimes being misunderstood or only partially understood may actually be exactly what's wanted. For example, consider a comedian trying to tell a joke without giving away the punch line too soon, or perhaps even intentionally allowing the audience to make erroneous assumptions about things it would have been easy enough to clarify from the start, all so that the desired entertainment effect can be achieved. Entertainment can be relaxing, exhilarating, or even educational, and is an important part of the human experience. Ludoviko Lazaro Zamenhof seems to have recognized this fact in his choice to directly provide support for it as a feature of the Esperanto language. In that same spirit, the Esper' language expands on this feature without actually violating it in any way, by extending the marking of where the word stem ends to any word, rather than just those with their noun ending removed, which has the side effect of returning a clarification which had been lost in the Esperanto language. It can be seen in earlier work of L.L.Z., known affectionately by his pen name "Doktoro Esperanto", that certain words had once been given the stress on their last syllable in the Esperanto language, but the final released version of the language showed no way of indicating such a thing and in fact stated in the rules of grammar that the stress was to always fall on the next to last syllable. However, in actual usage it is common to stress the lass syllable of a noun which has had it's noun ending replaced by the apostrophe character and you may occasionally hear the last syllable of a korelativo stressed in the Esperanto language even without any marker to indicate that something may be missing, like for example an implied adverbial ending. Of course, the original release of Esperanto also suggested little commas placed between the elements of a word, so it is easy to imagine the inventor of the language wanting to avoid combining that feature with some marking of where to place the stress in a given word, but the little commas seem to have fallen entirely out of use so this is no longer a concern.
With the stress clearly marked, the Esper' language is able to expand on the subtle distinction between pronouns ending in i' and verbal infinitives ending in 'i both in written and spoken from. As a result, both pronouns and correlatives from the Esperanto language have been inherited into the Esper' language as proforms with the final i being treated as a stressed suffix rather than a destressed role ending. Since most pronouns in the Esperanto language are single syllable, this causes a slight alteration in a very small number of words. If you have studied Esperanto, you may have wondered for example why "ili" isn't considered a verb, since it seems to have the infinitive ending, and the reason generally given is something to the effect of that it is a "word root" which may make one wonder just what words a person may form with such a root. Well, the answer in the Esperanto language to that question would be that "ilin" is the accusative case of "ili" and that's pretty much it. This of course simply leads to more questions, if you have a naturally curious mind. The Esperanto explanation of course stands in the Esper' language and it is perfectly acceptable to treat "ili" as a word root in its own right, but it also happens to be the word root "il" with a prefix attached indicating the concept of "some" with a range of meanings which includes that indication of the plural. This means thesecond person proform word root vi can also be made into the plural pronoun ivi indicating the concept of "you" in the plural, but more generally it means that any such word which may be basically an immutable particle word in the Esperanto language can be "decorated up" in the Esper' language to form any part of speech desired.
In the Esper' language, written and spoken stress are mainly a matter of choice, but the rule of thumb is that if a written word doesn't have a marker for where the stress goes and it is not obvious from context or known common usage, then the Esperanto rule of "stress on the next to last syllable" should generally be applied. This means that the plural pronoun ili' when written as ili may be read with the stress on the end because it is recognized as a pronoun, or may be spoken as if it were meant to represent the infinitive verb from il'i if the reader is more accustomed to the Esperanto word stress pattern or is not sure enough that the word was meant as a proform in the given context. Leaving the stress marker off in written form means leaving the interpretation of intended stress at the discretion of the reader, and using an "alternative stress pattern" in speech means leaving the interpretation of such a variation up at the discretion of the listener within the given context.
See also: Esper/Esper_for_Esperanto_Speakers
There is no rule in the Esper' language stating that a word element which serves one purpose can not also serve a different purpose, but rather the individual user of the language is encouraged to learn patterns which seem to make sense and apply them as needed to convey what is intended to be communicated. For example, if you are speaking with someone who you know thinks of a particular word element in a different way than you do, it may be best to simply avoid the use of that word element when possible and clarify your usage when it can't be avoided. We do this with other languages already so this is not something new to learn, but in the Esper' language it is acknowledged as a part of how the language works and grows and evolves. Feel free to push the limits when you feel its the right thing to do and to stay well within what you see as more "normal usage" when feel that is what's best.