A minim is a small amount of fluid. Specifically it is 1/60 of a fluid dram (British spelling drachm) or 1/480 of a fluid ounce. It is thus exactly 0.061 611 519 921 875 millilitres in the U.S. system and exactly 0.059 193 880 208 (3) millilitres in the imperial system (the notation (3) indicates the digit 3 is repeated infinitely).

In contrast with apothecaries' weight, apothecaries' measure is a system both recent and short-lived. It seems to have arisen with the United Kingdom's defining of the new imperial gallon in 1824, and is fully described at least as early as 1878 in the Weights and Measures Act. In the United Kingdom, the 1963 Weights and Measures Act provided for the abolition of the minim, fluid scruple , and fluid drachm, all already obsolete. Actual delegalization occurred on February 1, 1971.