'avocat' (legal sense) originates from Latin, specifically the word 'advocatus', where 'ad-' meant 'to/toward' and 'vocare' meant 'to call'. The 'avocat' (fruit) sense in French was borrowed later via Spanish forms from Nahuatl 'āhuacatl' (through Spanish 'aguacate').

'advocatus' (Latin) passed into Old French as 'avocat' and became the modern French 'avocat' meaning a legal advocate. Separately, the Nahuatl word 'āhuacatl' became Spanish 'aguacate' and was borrowed into French as 'avocat' (fruit), producing two distinct senses under the same spelling.

Originally (from Latin) it meant 'one called to aid' in legal contexts and evolved into the modern meaning 'lawyer/advocate'; the fruit sense originally referred to the Nahuatl-named fruit and came into French via Spanish, so the two senses converged in form though they have different origins.