ratter

One that catches or kills rats.

One who betrays or deserts another.

One who rats, or becomes a renegade; also, a workman who renders himself obnoxious to a trades-union. See ratting, 2.

One who catches rats; a rat-catcher.

An animal which catches rats, as a terrier.

One who, or that which, rats, as one who deserts his party.

Anything which catches rats; esp., a dog trained to catch rats; a rat terrier. See Terrier.

Anything which catches rats, especially a dog trained to catch them; a rat terrier.

One who rats; a traitor; a deserter.

any of several breeds of terrier developed to catch rats