'avo' originates from Modern English, specifically as an abbreviation of the word 'avocado', where 'avocado' entered English via Spanish 'aguacate' and ultimately from Nahuatl 'āhuacatl'.

'avo' developed as a colloquial shortening of 'avocado' (a word borrowed into English in the 18th–19th centuries from Spanish and Nahuatl) and became especially common in Australian English as 'avo'.

Initially it referred simply to the fruit 'avocado'; over time the short form 'avo' has retained that meaning and is also commonly used in reference to avocado-based dishes (e.g., avocado toast).