volatile (adj.)

1590s "fine or light," also "evaporating rapidly" (c. 1600), from French volatile, from Latin volatilis "fleeting, transitory; swift, rapid; flying, winged," from past participle stem of volare "to fly" (see volant). Sense of "readily changing, flighty, fickle" is first recorded 1640s. Volatiles in Middle English meant "birds, butterflies, and other winged creatures" (c. 1300).

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Definitions of volatile
volatile (adj.)
evaporating readily at normal temperatures and pressures;
volatile solvents
volatile oils
volatile (adj.)
liable to lead to sudden change or violence;
a volatile situation with troops and rioters eager for a confrontation
Synonyms: explosive
volatile (adj.)
marked by erratic changeableness in affections or attachments;
a flirt's volatile affections
Synonyms: fickle
volatile (adj.)
tending to vary often or widely;
volatile emotions
volatile stocks
volatile (n.)
a volatile substance; a substance that changes readily from solid or liquid to a vapor;
it was heated to evaporate the volatiles