British informal: to make a serious mistake or ruin something through incompetence.
To make a big mistake and ruin something.
3 meanings, ordered from most common to least. Color-coded by CEFR level.
To ruin or spoil something through a careless or stupid mistake.
"I completely cocked up the soufflé — I forgot to preheat the oven."
We've cocked it up, we've really cocked it up.
— John Cleese, Fawlty Towers (attributed in various interviews referencing the show's production)
To make a serious error that has damaging consequences for others.
"The government cocked up the vaccine rollout in the early stages."
(Literal, rare) To tilt or raise something upward at an angle, such as an ear or a hat brim.
"The dog cocked up its ears at the sound of the doorbell."
Originally referred to a hat brim being cocked (tilted) incorrectly or a gun hammer left unsafely raised; now entirely idiomatic.
To make a big mistake and ruin something.
Very common in British English. Can be used as a verb ('he cocked it up') or noun ('what a cock-up'). The noun form 'cock-up' is hyphenated. Considered mildly vulgar by some but widely used in British media and conversation. Not considered offensive enough to avoid in most adult contexts.
Natural word combinations native speakers use most often.
The five tense forms you'll use most often.
Listen to native speakers using "cock up" in real YouTube videos — click a clip to watch it on Looplines.
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