Lewis & Short

pūnītor, ōris, m. [punio].

  1. I. A punisher (post-class.): seditiosorum punitor acerrimus, Suet. Caes. 67; Val. Max. 6, 1, 8.
  2. II. An avenger: fuit ultor injuriae, punitor doloris sui, Cic. Mil. 13, 35: Crassianae stragis, Val. Max. 3, 4, 5.