Soul patch
A small tuft of hair just below the lower lip, above the chin.
Also: mouche, jazz dot
A soul patch is a small patch of beard under the lower lip. It became widely known among American jazz musicians in the 1950s and 1960s, who are often said to have found it comfortable when playing brass instruments. It is sometimes worn alone and sometimes with a moustache or goatee. It needs only a small area of growth, so even sparse beards can carry it.