Dear WO'N: Rules were made to be broken. My dictionary gives both: With only one "s" it would have long "a", so I like the two esses.
gas
n.,
pl. gas[es or gas[ses 7gas4iz8 5ModL, altered by Van Helmont (1577-1644), Belgian chemist (with g3 pronounced, as in Du, as a voiced fricative) < Gr chaos, air (see CHAOS), term used by Paracelsus6
1 the fluid form of a substance in which it can expand indefinitely and completely fill its container; form that is neither liquid nor solid; vapor
2 any mixture of flammable gases used for lighting, heating, or cooking
3 any gas, as nitrous oxide, used as an anesthetic
4 any substance, as phosgene, intentionally dispersed through the atmosphere, as in war, to act as a poison, irritant, or asphyxiant
5 various gaseous substances formed by living or decaying matter, esp. if formed in the stomach, bowels, etc.
6 [Colloq.] short for GASOLINE
>7 [Slang] a) idle or boastful talk b) something or someone that is very pleasing, exciting, amusing, etc. !the movie was a gas"
8 Mining a mixture of firedamp with air, that explodes if ignited
vt.
gassed, gas4sing
1 to supply with gas
2 to subject to the action of gas
3 to injure or kill by gas, as in war
>4 [Slang] to thrill, delight, amuse greatly, etc.
vi.
1 to give off gas
>2 [Slang] to talk in an idle or boastful way
adj.
of, using, or operated by gas
>gas it up [Colloq.] to supply (a vehicle) with gasoline
>step on the gas
1 [Slang] to press on the accelerator of an automobile
2 to hurry; move or act faster