slasher

Short definition from Wiktionary

Noun

1. 1
   One who slashes.
2. 2
   A machine for applying size to warp yarns.
3. 3
   A horror movie with graphic blood and violence; a slasher movie.
4. 4
   A murderer in such a film.
5. 5
   One who self-injures by cutting.
6. 6
   A tool for cutting undergrowth.
7. 7
   One who writes slash fiction and/or supports male/male ships.
8. 8
   A member of the 28th (North Gloucestershire) Regiment of Foot.