1. That part of the human body which is immediately below the ribs or thorax; the small part of the body between the thorax and hips. Chaucer. I am in the waist two yards about. Shak. 2. Hence, the middle part of other bodies; especially (Naut.), that part of a vessel's deck, bulwarks, etc., which is between the quarter-deck and the forecastle; the middle part of the ...