'Angus' originates from Gaelic, specifically the word 'Aonghas' (from Old Irish 'Oengus'), where 'aon' meant 'one' and 'gus' meant 'choice' or 'strength'.

'Angus' changed from the Old Irish name 'Oengus' into the Scottish Gaelic form 'Aonghus' and later entered English as the modern proper name 'Angus'.

Initially, it meant 'one choice' or 'unique strength' as a personal name; over time it became used as a given name, a place name, and the name of a cattle breed.