evaporation n.

word-forming element, in English meaning usually "out of, from," but also "upwards, completely, deprive of, without," and "former;" from Latin ex "out of, from within; from which time, since; according to; in regard to," from PIE *eghs "out" (source also of Gaulish ex-, Old Irish ess-, Old Church Slavonic izu, Russian iz). In some cases also from Greek cognate ex, ek. PIE *eghs had comparative form *eks-tero and superlative *eks-t(e)r-emo-. Often reduced to e- before -b-, -d-, -g-, consonantal -i-, -l-, -m-, -n-, -v- (as in elude, emerge, evaporate, etc.).

late 14c., from Anglo-French vapour, Old French vapor "moisture, vapor" (13c., Modern French vapeur) and directly from Latin vaporem (nominative vapor) "a warm exhalation, steam, heat," which is of unknown origin. Vapors "fit of fainting, hysteria, etc." is 1660s, from medieval notion of "exhalations" from the stomach or other organs affecting the brain.

early 15c., "draw off (humors or spirits) as vapor," from Late Latin evaporatum, past participle of evaporare "disperse in vapor" (see evaporation). Intransitive sense by 1560s. Figurative use by 1610s. Related: Evaporated; evaporating. Evaporated milk (1870) is processed milk with some of the liquid removed by evaporation; it differs from condensed milk in being unsweetened.