I. ˈki-lər noun
Date: 15th century
1. : one that kills
2. : killer whale
3.
a. : one that has a forceful, violent, or striking impact
b. : one that is extremely difficult to deal with
II. adjective
Date: 1951
1. : strikingly impressive or effective
a killer smile
a killer résumé
2. : extremely difficult to deal with
a killer fastball
also : causing death or devastation
a killer tornado