- ex- prefix, in English meaning mainly "out of, from," but also "upwards, completely, deprive of, without," and "former;" from L. ex "out of, from within," from PIE *eghs "out" (Cf. Gaul. ex-, O.Ir. ess-, O.C.S. izu, Rus. iz). In some cases also from Greek cognate ex, ek. PIE *eghs had comparative form *eks-tero and superlative *eks-t(e)r-emo-.
Etymology dictionary. 2014.