The Collaborative International Dictionary of English v.0.48:
Hellhound \Hell"hound`\, n. [AS. hellehund.] A dog of hell; an agent of hell. [1913 Webster] A hellhound, that doth hunt us all to death. --Shak. [1913 Webster]WordNet (r) 3.0 (2006):
hellhound n 1: a very evil man 2: (Greek mythology) the three-headed dog guarding the entrance to Hades; son of Typhon [syn: Cerberus, hellhound]