is, properly, one whose lot is cast in with another. As the Queen does not lose by marriage her separate existence, like other women, her husband is called a consort, because he consorts with the Queen, but does not share her sovereignty.
“Wilt thou be our consort?”
Shakespeare: Two Gentlemen of Verona, iv. 1.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894