ounce

Concise Oxford English Dictionary © 2008 Oxford University Press:
ounce1

▶noun

• 1 (abbrev.: oz) a unit of weight of one sixteenth of a pound avoirdupois (approximately 28 grams).

  ■ a unit of one twelfth of a pound troy or apothecaries' measure, equal to 480 grains (approximately 31 grams).

• 2 a very small amount.

– origin ME: from OFr. unce, from L. uncia ‘twelfth part (of a pound or foot)’; cf. inch1.

Concise Oxford English Dictionary © 2008 Oxford University Press:
ounce2

▶noun a snow leopard.

– origin ME: from OFr. once, earlier lonce (the l- being misinterpreted as the definite article), based on L. lynx, lync- (see lynx).