a prefix meaning “out of,” “from,” and hence “utterly,” “thoroughly,” and sometimes meaning “not” or “without” or indicating a former title, status, etc.; freely used as an English formative: exstipulate; exterritorial; ex-president (former president); ex-member; ex-wife .
prefix, in Eng. meaning mainly "out of, from," but also "upwards, completely, deprive of, without," and "former;" from L. ex "out of," from PIE *eghs "out" (cf. Gaul. ex-, O.Ir. ess-, O.C.S. izu, Rus. iz). In some cases also from Gk. cognate ex, ek. It has stood on its own since 1929 as abbreviation for ex-wife, ex-husband, etc.