The term 'altar assent' is a phrase used to describe the agreement of two people to marry each other. The crossword solutions for this term are OUI (3 letters), AYE (3 letters), NOD (3 letters), and IDO (3 letters). OUI is a French word meaning 'YES', AYE is an English word meaning 'YES', NOD is an English word meaning 'to indicate agreement by nodding one's head', and IDO is an English word meaning 'to agree to marry'. All four words signify agreement or acceptance, which is why they are used to represent the term 'altar assent'.