FOSS, or FOSSE, in Fortification, &c. a ditch or moat. The word is French, formed of the Latin participle fossus, of the verb fodio, "I dig."
Foss, 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.
Foss is particularly used for the cavity or denture in the back part of the neck.