Fosse, in fortification, &c., a ditch or moat. The word is French, formed of the Latin participle fossum, of the verb fodio "I dig."

Fossa, Fossa, in anatomy, a kind of cavity in a bone, with a large aperture, but no exit or perforation. When the aperture is very narrow, it is called a sinus.

Fossa is particularly used for the cavity or denture in the back part of the neck.

FOSSA MAGNA, or NAVICULARIS, is an oblong cavity, forming the inside of the pudendum muliebre, and which presents itself upon opening the labia; and in the middle whereof are the carunculae myrtiformes. See ANATOMY, p. 470.