fluid ounce

Noun

 * 1) Any of various units of volume used for liquid measure, all approximately 1.73–1.83 cubic inches or 28.4–30 milliliters.
 * 2)  A unit of volume equal to one sixteenth of a US pint or approximately 29.6 ml
 * 3)  A unit of volume equal to one twentieth of an imperial pint or approximately 28.4 ml