An avoirdupois ounce, weighing 1⁄16 of an avoirdupois pound, or 28.3495 grams.
A troy ounce, weighing 1⁄12 of a troy pound, or 480 grains, or 31.1035 grams.
A US fluid ounce, with a volume of 1⁄16 of a US pint, 1.8047 cubic inches or 29.5735 millilitres.
A British imperial fluid ounce, with a volume of 1⁄20 of an imperial pint, 1.7339 cubic inches or 28.4131 millilitres.
(figurative) Any small amount, a little bit.
(now archaic) A large wild feline, such as a lynx or cougar.
Synonym of snow leopard, Panthera uncia.
(cryptozoology) Synonym of onza, a particularly aggressive cougar or jaguarundi in Mexican folklore.