a prefix occurring originally in loanwords from Greek, where it was joined to verbs, deverbal forms, and other parts of speech. Among its functions in Greek, apo- has the spatial sense "away, off, apart" ( apogee; apocope; apostasy; apostrophe ); it occurs with deverbals that denote a response or defense ( apodosis; apology ) and is found on verbs having perfective force relative to a corresponding simple verb ( apoplexy; aposiopesis ). In modern scientific coinages in English and other languages, apo- marks things that are detached, separate, or derivative ( apocarpous; apoenzyme ).
Also, esp. before a vowel, ap- .
[ apó; akin to OFF, Skt apa, L ab ]