Like English, D'ni is a non-inflected language. Therefore, prepositions are very important. They are mostly prefixes connected to words with apostrophes.
The prepositions attested are
- be 'to', which can used if someone is giving something to someone (dotagen b'set ‘is giving to us’), to express amount with numbers (b'vat ‘to five’), to show direction (relena b'retalío ‘the journey to the surface’) and, like English, to form the infinitive of verbs (rebishta kodosëen b'mes ‘the tunnel was designed to require’)
- fe 'along/at', to show something be done on the surface of something (tornen f'repradtí ‘it spits at the rocks’) and the expression f'túgo, ‘on foot’ is attested
- xe 'for' when it means 'towards the goal of', in xregicath ‘for the safety’
- me 'from/of', to show origin (dorísloen remarg melin m'reprad ‘dissolving the outer layer from the rock’) or composition (erthbantí me kílentí ‘a series of steps’)
- ne 'around', to show direction of motion
- te 'by/with/in/of', which has the same function as the Latin ablative. It expresses instrument, or something that happens with something else (trebigto ‘with the blessing’, tre'irvantí ‘along with the minerals’) and place (regalpotí tretalío ‘the caves at the surface’)
- ben is a different kind of preposition; it means 'during, for (a time)' or 'instead' when it means 'in exchange or equivalence with', in ferem ben erthgor tona ‘dry for a long time’
Oftentimes, prepositions are contracted.
- When the word does not begin with an article, the preposition's becomes a prefix and the e is replaced with an apostrophe (re'irvantí, t'Gen, b'Yavo, kortí'nea)
- When the word does begin with an article (re or erth), the preposition becomes a prefix and loses the e altogether (trebigto 'with the blessing', terthtes 'of a group')
The above rules also apply to the conjunction ga, 'and'.
Ben is never contracted.
The word ox 'of' is an individual word when the noun is modified with a following adjective, otherwise it is a suffix. It means direct possession.
- rekorox Gen 'the book of Gehn'
- rekor prin ox Gen 'the small book of Gehn' (here the adjective prin intervenes between the noun and ox)
The word co also means 'of' but in the meaning of characteristics/properties.