'custardy' originates from English, specifically the word 'custard' combined with the suffix '-y', where 'custard' originated from Old French 'croustade' meaning 'a tart (from crust)' and the suffix '-y' meant 'characterized by'.

'custard' changed from Old French 'croustade' (also Medieval Latin/Italian cognates such as 'crostata') into Middle English forms like 'croustade'/'crustade' and eventually became the modern English 'custard'; adding the adjective-forming suffix '-y' produced 'custardy'.

Initially, 'custard' referred to 'a tart or pie (a crusted dish)', but over time it evolved into its modern meaning of 'a sweet, creamy filling or dessert'; consequently, 'custardy' came to mean 'having the qualities of custard' (thick, creamy).