troy ounce vs apothecaries' ounce

troy ounce and apothecaries' ounce both are nouns.

Word	Noun	Adjective	Verb	Adverb
troy ounce	Yes	No	No	No
apothecaries' ounce	Yes	No	No	No

As nouns, troy ounce and apothecaries' ounce are synonyms defined as:

troy ounce and apothecaries' ounce: a unit of apothecary weight equal to 480 grains or one twelfth of a troy pound

Other synonyms of troy ounce include ounce.

troy ounce (noun)	apothecaries' ounce (noun)
a unit of apothecary weight equal to 480 grains or one twelfth of a troy pound	a unit of apothecary weight equal to 480 grains or one twelfth of a troy pound