- inchAn English unit of length equal to 1/12 of a foot or 2.54 cm.
- ounceAn avoirdupois ounce, weighing ¹⁄₁₆ of an avoirdupois pound, or 28.349523125 grams.
- ouguiyaThe currency of Mauritania, divided into five khoums.
- uncialOf or relating to an ounce, or an inch, especially to letters printed an inch high.
- onzaA traditional Spanish unit of mass, equivalent to about 28.76 g.
- onçaA traditional Portuguese unit of mass, usually equivalent to 28.7 g.
- unciaThe Roman ounce, 1/12 of a Roman pound.