kill off
phrasal verb.phrasal verb. to eliminate or destroy something completely — often used for ending a competition, a story element, or a biological entity.
phrasal verb. to cause the complete destruction or elimination of something; often used in contexts of ending a competition, a story element, or a biological entity. The phrasal verb is separable in certain syntactic constructions but typically used as an inseparable unit.
The new policy will kill off the old system.
The author decided to kill off the main character in the second chapter.
The virus was designed to kill off all infected cells in the body.
From kill + off.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
typically followed by a noun indicating what is being destroyed or eliminated.
contrast with 'kill' (more general) and 'eliminate' (more formal); 'kill off' implies total eradication rather than mere harm.
The company decided to kill of the outdated product line.The company decided to kill off the outdated product line.the particle 'off' is required; 'kill of' is not a valid construction.
Last updated April 24, 2026