Definition: A weight containing 480 g, or 1/12 pound troy and apothecaries' weight, or 437.5 g, 1/16 pound avoirdupois. The apothecary oz (used in the USP) contains 8 drams and is equivalent to 31.10349 g; the avoirdupois oz is equivalent to 28.35 g.
[L. uncia, the twelfth part (of a pound or foot) hence also inch]
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Examples: glitazone, GI cocktail, etc.