A preposition is a word that expresses a relationship between one noun or noun phrase and another word or element in the same sentence:
|Trans la fluvio e tra la bosko, che Avino ni iras.||Over the river and through the woods, to Grandmother’s house we go.|
|Violinagar dum ke Roma brulas||To fiddle while Rome burns|
|Ne kun foxo. Ne en buxo. Nek en domo o kun muso.||Not in a box. Not with a fox. Not in a house. Not with a mouse.|
In Ido, prepositions never end a sentence, as they often do in English:
|Pro quo vu facis to?||What did you do that for?|
|Pri quo esas ca filmo?||What is this movie about?|
There is also an “anything” preposition in Ido, ye, which has no definite meaning of its own but is used when no other preposition seems appropriate. It is often used to translate “at” with reference to time or place.
|ye la lasta foyo||the last time (something happened)|
|il prenis el ye la manuo||he took her by the hand|
|ye dimezo||at noon|
When describing a change in location, if the preposition used doesn’t by itself indicate it — and nothing else in the sentence does, either — one can prefix the preposition with ad, with or without a hyphen, somewhat like to in English into, onto:
|la reklamisto duktis sua automobilo en la turbo||the publicist drove her car (around) in the crowd|
|la reklamisto duktis sua automobilo aden (or ad-en) la turbo||the publicist drove her car into the crowd|
|Do, se vu deziras, me pozos la pafilo sur la tablo||
So, if you want, I’ll put the gun on the table
(motion onto already implied, since the gun is obviously not yet on the table)
Prepositions can be changed into other parts of speech by the addition of -a, -e, -o, etc. if the meaning allows:
|kontree||on the contrary|
|kontreajo||the contrary, opposite|
The prepositions en, ek, and per, however, do not take suffixes directly, but use separate roots: intern-, extern-, and mediac-.
There’s also the strange case of ultre, derived from ultra, meaning “beyond due limit”, “extreme”, as in ultra zelo “extreme zeal”. In its adverbial form ultre, it functions only as a preposition meaning “in addition to”, as in ultre Ido, me studias anke la hovita “besides Ido, I also study hovitos”. For an adverbial meaning, one must use extreme “extremely” for the one sense or pluse “additionally” for the other.
One can freely use prepositions before infinitive verbs, but di and ad are usually dropped when the context is sufficiently clear.
il esas malada pro tro laborir
(o pro troa laboro)
|he’s sick from working too much|
|l’ideo lavar la manui pos uzir la latrino esis klare stranja ad ilu||the idea of washing his hands after using the restroom was clearly foreign to him|
Because prepositions are also used as prefixes to verbs, one might occasionally need to rephrase oneself avoid ambiguity:
pos datizir cheko
(pos la datizir cheko or datizinte cheko)
|after dating a check|
|posdatizir cheko||to have postdated a check|