Indo-Iranian can be subdivided into the Indo-Aryan and Iranian branches. It is believed that speakers of these languages referred to themselves as 'ārya-' ‘Aryans’.[1]
The IE consonant system can be divided into three main categories: the stops, often denoted with a capital "T", the resonants (also called sonorants), referenced by the letter "R", and the laryngeals, represented by "H". For the sake of clarity, laryngeals will be treated along vowels. The only sound that is not part of any of these sets of consonants is the sibilant *s.
Proto-Indo-European nominals is a set of the IE vocabulary that encompasses adjectives, nouns and pronouns. All of these share common morphological features.
PIE is classically believed to have had eight inflectional cases: nominative, vocative, accusative, genitive, dative, ablative, locative, and instrumental. Unlike most daughter languages (i.e latin, Attic, Sanskrit), IE nominals do not typically belonged to a set of normalized declensions, but they could be divided in two main categories: thematic and athematic.
mention thematic and athematic
PIE is believed to have had three genders: masculine, feminine, and neuter. The masculine and feminine are often said to belong to the "animate" gender, and the neuter would represent the "inanimate".
This is because it is widely believed that at some stage of PIE's development (which highly is debated), there where only these two genders. Nouns
Proto-Indo-European had two different roots to refer to the number one, which are generally distinguished by the manes "the one together" and "the one alone", in reference to their semantic differences. The "one together" formed words indicating one same identity, it generally unified two or more different things into a single one. English words deriving from the one together include "same" and "similar", which exemplify the meaning of the root, since "same" indicates two or more things that are actually one single thing, and "similar" is used to say that two things are if they were one, or in other words they look alike.
In the other hand, the one alone was used to form words meaning singleness or uniqueness, English words deriving from it include "one", "unique", "only", "universal".
Beekes, Robert S. P. (2011). Michiel de Vaan (ed.). Comparative Indo-European Linguistics: An Introduction. revised and corrected by Michiel de Vaan (2nd ed.). Amsterdam, Philadelphia: John Benjamins Publishing Company.
Clackson, James (2007). Indo-European Linguistics: An Introduction. Cambridge Textbooks in Linguistics. Cambridge: Cambridge University Press.
Ringe, Don (2006). From Proto-Indo-European to Proto-Germanic. Oxford University Press.
Fortson, Benjamin W. (2004). Indo-European Language and Culture: An Introduction. Oxford: Blackwell.