- noun somebody who kills
- noun a person or disease which kills
- noun (something) superlative. Killer-diller was an Americanism of the 1940s which was briefly in vogue in Britain in the late 1950s among teddy boys and bohemians. Killer was a popular teenage term in the USA, particularly among black youth in the 1960s and 1970s, spreading to Britain and Australia in the 1980s with disco and hip hop music, break dancing, etc.