1. ex- a prefix occurring orig. in loanwords from Latin, meaning “out, out of, away, forth” (egregious; exclude; exhale; exit; export; extract), used also to signify that the action of a base verb has been carried to a conclusive point (effect; effete; erase; exaggerate; excite; exhaust), esp. in causative formations (evacuate; effeminate; exhilarate; expurgate) or privative formations, including adjectives (emasculate; enervate; exonerate; exsanguine).
2. ex- a prefixmeaning “former,”“formerly having been”: ex-member; ex-wife.; exarch.
3. ex- a prefix similar in meaning to ex-1, occurring orig. in loanwords from Greek: exegesis.
Etymology: (< Gk, prefixal use of ex, ek, out (of), from, beyond; cf. ex -1)
1. (prefix)ex- former the ex-secretary of Education; my ex-boyfriend
Definition of 'ex-'
Webster Dictionary
1. ex- a prefix from the latin preposition, ex, akin to Gr. 'ex or 'ek signifying out of, out, proceeding from. Hence, in composition, it signifies out of, as, in exhale, exclude; off, from, or out. as in exscind; beyond, as, in excess, exceed, excel; and sometimes has a privative sense of without, as in exalbuminuos, exsanguinous. In some words, it intensifies the meaning; in others, it has littleaffect on the signification. It becomes ef- before f, as in effuse. The form e- occurs instead of ex- before b, d, g, l, m, n, r, and v, as in ebullient, emanate, enormous, etc. In words from the French it often appears as es-, sometimes as s- or e-; as, escape, scape, elite. Ex-, prefixed to names implying office, station, condition, denotes that the person formerly held the office, or is out of the office or condition now; as, ex-president, ex-governor, ex-mayor, ex-convict. The Greek form 'ex becomes ex in English, as in exarch; 'ek becomes ec, as in eccentric
Definitions of ex- 
