Definition of "retractor"

One who, or that which, retracts.  examples

In breech-loading firearms, a device for withdrawing a cartridge shell from the barrel.  examples

(chess) A chess puzzle in which a number of moves are retracted and the solver is challenged to reach an alternate outcome.  examples

A surgical instrument used to hold apart the edges of an incision or wound.  examples

A bandage to protect soft parts of the body from injury by a surgical saw.  examples

(zoology) A muscle serving to draw in any part.