apothecaries' weight

WordReference Random House Unabridged Dictionary of American English © 2025

apoth′ecaries' weight′, 

1. a system of weights used chiefly in compounding and dispensing drugs: 20 grains = 1 scruple (℈);
   3 scruples = 1 dram ();
   8 drams = 1 ounce );
   12 ounces = 1 pound. The grain, ounce, and pound are the same as in troy weight, the grain alone being the same as in avoirdupois weight.

• 1755–65

Collins Concise English Dictionary © HarperCollins Publishers::

apothecaries' weight noun

1. a system of weights, formerly used in pharmacy, based on the Troy ounce, which contains 480 grains. 1 grain is equal to 0.065 gram