philosophers' wool vs philosopher's wool

philosophers' wool and philosopher's wool both are nouns.

Word	Noun	Adjective	Verb	Adverb
philosophers' wool	Yes	No	No	No
philosopher's wool	Yes	No	No	No

As nouns, philosophers' wool and philosopher's wool are synonyms defined as:

philosophers' wool and philosopher's wool: oxide of zinc; a white powder used as a pigment or in cosmetics or glass or inks and in zinc ointment

Other synonyms of philosophers' wool include flowers of zinc, zinc oxide.

philosophers' wool (noun)	philosopher's wool (noun)
oxide of zinc; a white powder used as a pigment or in cosmetics or glass or inks and in zinc ointment	oxide of zinc; a white powder used as a pigment or in cosmetics or glass or inks and in zinc ointment