mé·sal·li·ance 
(mā-zălē-əns, mā′ză-lyäɴs)
(mā-zălē-əns, mā′ză-lyäɴs)n.
A marriage with a person of inferior social position.
[French : més-, bad (from Old French mes-; see MIS-1) + alliance, alliance (from Old French aliance; see ALLIANCE).]