preposition (n.) Look up preposition at Dictionary.com
late 14c., from Latin praepositionem (nominative praepositio) "a putting before, a prefixing," noun of action from past participle stem of praeponere "put before," from prae "before" (see pre-) + ponere "put, set, place" (see position (n.)). In grammatical use, a loan-translation of Greek prothesis, literally "a setting before."