'adpromissor' originates from Latin, specifically the word 'adpromissor', where 'ad-' meant 'toward' and 'promissor' meant 'one who promises'.

'adpromissor' has remained largely unchanged from its Latin origins, retaining its meaning in legal contexts.

Initially, it meant 'one who promises or guarantees', and this meaning has largely remained the same in modern usage.