Hobnail \Hob"nail`\, n. [1st hob + nail.] 1. A short, sharp-pointed, large-headed nail, -- used in shoeing houses and for studding the soles of heavy shoes. 2. A clownish person; a rustic. --Milton. {Hobnail liver} (Med.), a disease in which the liver is shrunken, hard, and covered with projections like hobnails; one of the forms of cirrhosis of the liver.