The Collaborative International Dictionary of English v.0.48:
Volatile \Vol"a*tile\, a. [F. volatil, L. volatilis, fr. volare
to fly, perhaps akin to velox swift, E. velocity. Cf.
1. Passing through the air on wings, or by the buoyant force
of the atmosphere; flying; having the power to fly. [Obs.]
2. Capable of wasting away, or of easily passing into the
aeriform state; subject to evaporation.
Note: Substances which affect the smell with pungent or
fragrant odors, as musk, hartshorn, and essential oils,
are called volatile substances, because they waste away
on exposure to the atmosphere. Alcohol and ether are
called volatile liquids for a similar reason, and
because they easily pass into the state of vapor on the
application of heat. On the contrary, gold is a fixed
substance, because it does not suffer waste, even when
exposed to the heat of a furnace; and oils are called
fixed when they do not evaporate on simple exposure to
3. Fig.: Light-hearted; easily affected by circumstances;
airy; lively; hence, changeable; fickle; as, a volatile
You are as giddy and volatile as ever. --Swift.
Volatile alkali. (Old Chem.) See under Alkali.
Volatile liniment, a liniment composed of sweet oil and
ammonia, so called from the readiness with which the
Volatile oils. (Chem.) See Essential oils, under