volatile
Pronunciation: /ˈvɒlətʌɪl/
adjective
- 1(of a substance) easily evaporated at normal temperatures: volatile solvents such as petroleum ether, hexane, and benzene

Origin:
Middle English (in the sense 'creature that flies', also, as a collective, 'birds'): from Old French volatil or Latin volatilis, from volare 'to fly'