'Cerberus' definitions:

Definition of 'Cerberus'

noun

(Greek mythology) the three-headed dog guarding the entrance to Hades; son of Typhon [syn: Cerberus, hellhound]

From: GCIDE

Cerberus \Cer"be*rus\, n. [L. Cerberus (in sense 1), gr. ?.] [1913 Webster]
1. (Class. Myth.) A monster, in the shape of a three-headed dog, guarding the entrance into the infernal regions, Hence: Any vigilant custodian or guardian, esp. if surly. [1913 Webster]
2. (Zool.) A genus of East Indian serpents, allied to the pythons; the bokadam. [1913 Webster]