Say It: \ˌmā-ˌzal-ˈyäⁿs/
Part of Speech: noun
Definition (as defined by Merriam-Webster): a marriage with a person of inferior social position.
Used in a Sentence (aka How I Found It): “So Lady Rose MacClare is a mésalliance.” -Dowager Countess Crawley in “Episode Eight” Downton Abbey Season Five.
Origin: French, first used in 1782.