volatile
1. vol.a.tile \'va:l-*t-*l, esp Brit -*-.ti-l\ n [ME volatil, fr. OF, fr. volatilie group of birds, fr. ML volati]lia, fr. L, neut. pl. of volatilis winged, volatile 1: a winged creature (as a bird or insect) 2: a volatile substance 2. volatile aj [F, fr. L volatilis, fr. volatus, pp. of volare to fly] 1: FLYING : having the power to fly 2: readily vaporizable at a relatively low temperature 3a: LIGHTHEARTED, LIVELY 3b: easily aroused 3c: tending to erupt into violent action : EXPLOSIVE 4: CHANGEABLE, FICKLE 5: EVANESCENT, TRANSITORY
Webster's English Dictionary