Manx \Manx\, a. Of or pertaining to the Isle of Man, or its inhabitants; as, the Manx language. {Manx cat} (Zo["o]l.), a breed of domestic cats having a rudimentary tail, containing only about three vertebrae. {Manx shearwater} (Zo["o]l.), an oceanic bird ({Puffinus anglorum}, or {P. puffinus}), called also {Manx petrel}, {Manx puffin}. It was formerly abundant in the Isle of Man.