'half-ass' originates from American English slang, combining 'half' meaning 'partially' and 'ass' as a derogatory term for effort or competence.

'half-ass' evolved from the phrase 'half-assed,' which was used in the mid-20th century to describe something done poorly or with little effort.

Initially, it meant 'partially done,' but over time it evolved into its current meaning of 'done with little effort or care.'