ex-

The prefix ex- first appeared in English words in the Middle English in words borrowed from French. It comes from the Latin where it was both a prefix and a preposition. Later in the Middle English period it became a productive prefix. It is akin to Ancient Greek (εκ-, εχ-, εχω-). Its meaning ranges from1. "out, away" (example , ex-dividend date)2. "up" (abstract meaning indicating increase or strengthening of a particular quality, often negative - sometimes called intensive) (example , )3. "former, prior" (examples , ) This is a much later development and did not exist in Latin.
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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 little affect 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.
  

= sometime + Nombre.
Ex: One of the most successful is the system devised by Dyson, sometime editor of CA.
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* ex-amante = old flame.
* ex-libris = ex-libris plate, bookplate [book plate].
* ex-novio = old flame.
* ex oficio = ex officio.
* ex profeso = purposely.