Latin praepono to put or place before, to place first' is where the noun praepositio 'a setting before, prefixing' is derived from (its past particple praepositum). To augment what Faldage said: Sanskrit, Greek, and German exhibit a process called tmesis (literally 'a cutting' in Greek) where a verbal particle which is normally prefixed is separated in certain forms of the verb: e.g., German aufpassen 'to pay attention' yields pass(e) auf in the singular, informal imperative. Some languages have prepositions and others have postpositions. Some think that postpositions might eventually turn into inflectional case endings if given enough time.