Ambergris ( or ; ; ), ambergrease, or grey amber is a solid, waxy, flammable substance of a dull grey or blackish colour produced in the digestive system of sperm whales. Freshly produced ambergris has a marine, fecal odor. It acquires a sweet, earthy scent as it ages, commonly likened to the fragrance of isopropyl alcohol without the vaporous chemical astringency.
Ambergris has been highly valued by perfume makers as a fixative that allows the scent to last much longer, although it has been mostly replaced by synthetic ambroxide. Dogs are attracted to the smell of ambergris and are sometimes used by ambergris searchers.