'cock-up' originates from English, combining 'cock' (from Old English 'cocc' originally meaning 'rooster' and later used in various verbal senses) and 'up' (from Old English 'upp' meaning 'upwards' or 'in a raised position'). The compound in its modern slang sense is British.

'cock up' existed earlier in English with senses like 'to set on end' or 'to tilt'; by the early 20th century the verb sense broadened, and the noun 'cock-up' meaning 'a blunder or mess' became established in British informal usage (attested in the 20th century, especially around the 1940s).

Initially related to physical positioning or setting something up, the phrase shifted over time to mean 'to make a mess of something' or 'to bungle' in modern informal English.