onza [Spanish]

Like so many terms for units, the onza derives from the Latin uncia, ¹/₁₂th of the Roman libra.

For the Portuguese unit, see onça.

1

A unit of mass in Spain and South America, 20th century:

Chile, Cuba, Guatemala, Nicaragua, Peru, and Spain	approximately 28.750 grams (UN 1966)
Colombia	= 1/16 libra = 31.25 grams (UN 1966)
Costa Rica [Costa Rica. Ministerio de formento.] Medidas y pesas del sistema métrico, y tablas de equivalencia con las antiguas. San José de Costa Rica: Imprenta nacional, 1885.	= 28.7539 grams. The apothecary's onza was identical.
Dominican Republic	= 1 ounce avoirdupois, approximately 28.35 grams (UN 1966)
Honduras (and see definition 2)	28.755 grams (UN 1966)
Paraguay	approximately 28.688 grams (UN 1966)
Mexico	28.775 grams (UN 1966)

In Spain, the onza also appears in apothecaries' weight, = 1/12 libra, about 28.8 grams.

In Honduras, a unit of liquid capacity, approximately 28.8 milliliters.