The Collaborative International Dictionary of English v.0.48:
Lantern-jawed \Lan"tern-jawed`\, a. Having lantern jaws or long, thin jaws; as, a lantern-jawed person. [1913 Webster]WordNet (r) 3.0 (2006):
lantern-jawed adj 1: having a protruding jaw giving the face a gaunt appearance