means A penetrating, animal-warm fragrance — originally a substance from a gland of the male musk deer, now mostly synthetic — used as a base note in perfumes, or by extension any heavy earthy scent.

from From Middle English via Old French 'musc' and Late Latin 'muscus,' which came from Greek 'moskhos.' The trail runs back through Persian 'mushk' to Sanskrit 'mushka,' meaning 'testicle' (literally a 'little mouse,' from 'mush,' mouse) — a blunt nod to the scrotum-shaped gland sac on the musk deer from which the perfume was harvested. So the most refined of fragrances carries, etymologically, the earthiest of names.