 He married María Rosa Lida de Malkiel, a philologist and literary critic from Argentina, in 1948.During a period when etymology was receding from prominence in linguistics, Malkiel was both one of its chief champions and most rigorous theorists.Best known for his work on the role of sound in the development of suffixes, Malkiel coined the term lexical polarization to describe the influence in sound words tend to have over the development of their opposites, when antonyms occur in pairs.