Cerberus
Cerberus , noun
[L. Cerberus (in sense 1), gr. {not transcribed}.]
1.
(Class. Mythology) 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.
2.
(Zoology) A genus of East Indian serpents, allied to the pythons; the bokadam.