The Collaborative International Dictionary of English v.0.48:
nonvolatile \nonvolatile\ adj. not readily evaporated. Opposite of volatile. [WordNet 1.5]WordNet (r) 3.0 (2006):
nonvolatile adj 1: not volatilizing readily; "a nonvolatile acid" [syn: nonvolatile, nonvolatilizable, nonvolatilisable] [ant: volatile]