kill off

To cause all or most members of a group of living things to die.

• The spray killed off the insects.
• Hunting killed off the island’s largest birds.
• Will this treatment kill off all the bacteria?

How to use it: kill something off (The disease killed most of the fish off.)

Similar words: wipe out, exterminate

Common phrases: kill off insects, kill off a species

For a writer, to make a character die so they no longer appear in the story.

• They killed off my favourite character.
• The author killed her hero off halfway through the book.
• Will the producers kill off another character this season?

How to use it: kill someone off (The writers killed the detective off in the finale.)

Common phrases: kill off a character, kill off someone

To make something stop happening or prevent it from continuing.

• The delay killed off our plans.
• Higher prices have killed off demand for these products.
• Will the new rules kill off small businesses?

How to use it: kill something off (The cuts killed the project off before it started.)

Similar words: end, destroy, put an end to

Common phrases: kill off competition, kill off a project