ounce

plural ounces

1. An avoirdupois ounce, weighing ¹⁄₁₆ of an avoirdupois pound, or 28.349523125 grams.

   Synonyms: oz., ℥, uncia

2. A troy ounce, weighing ¹⁄₁₂ of a troy pound, or 480 grains, or 31.1034768 grams.
3. A US fluid ounce, with a volume of ¹⁄₁₆ of a US pint, 1.804688 cubic inches or 29.5735295625 millilitres.
4. A British imperial fluid ounce, with a volume of ¹⁄₂₀ of an imperial pint, 1.733871 cubic inches or 28.4130625 millilitres.
5. figurativelyAny small amount, a little bit.

   He didn't feel even an ounce of regret for his actions.

plural ounces

1. archaicA large wild feline, such as a lynx or cougar.First known use 14th c.

   Halloa! another prey, The nimble Antelope! The ounce is freed; one spring, And his talons are sheath’d in her shoulders, And his teeth are red in her gore.

   1801, Robert Southey, “(please specify the page)”, in Thalaba the Destroyer, volume (please specify |volume=I or II), London: […] [F]or T[homas] N[orton] Longman and O[wen] Rees, […], by Biggs and Cottle, […], →OCLC

   2 more examples

   The Ounce or the vvilde Cat, is as big as a mungrell dog, this creature is by nature feirce, and more dangerous to bee met vvithall than any other creature, not fearing eyther dogge or man; […]

   1634, William Wood, “Of the Beasts that Live on the Land”, in New Englands Prospect. A True, Lively, and Experimentall Description of that Part of America, Commonly Called New England; […], London: […] Tho[mas] Cotes, for Iohn Bellamie, […], →OCLC, 1st part, page 23

   ... their human countenance, Express resemblance of the gods, is chang'd Into some brutish form of Woolf, or Bear, Or Ounce, or Tiger, Hog, or bearded Goat, All other parts remaining as they were ...

   Comus

   1634 October 9 (first performance; Gregorian calendar), [John Milton], edited by H[enry] Lawes, A Maske Presented at Ludlow Castle, 1634: […] [Comus], London: […] [Augustine Matthews] for Hvmphrey Robinson, […], published 1637, →OCLC; reprinted as Comus: […] (Dodd, Mead & Company’s Facsimile Reprints of Rare Books; Literature Series; no. I), New York, N.Y.: Dodd, Mead & Company, 1903, →OCLC

2. Synonym of snow leopard, Panthera uncia.First known use 18th c.

   Synonyms: snow leopard, Panthera uncia

3. biologySynonym of onza, a particularly aggressive cougar or jaguarundi in Mexican folklore.

   The ounce, a leopard-like creature, is dreaded for its depredations by the Indians of Brazil.

   1911, James George Frazer, The Golden Bough, volume 8, page 235

   Synonyms: onza