(Spouze, 1 syl.) means one whom sponsors have answered for. In Rome, before marriage, the friends of the parties about to be married met at the house of the woman's father to settle the marriage contract. This contract was called sponsalia (espousals); the man and woman were spouses. The contracting parties were each asked, “An spondes ” (Do you agree?), and replied “Spondeo ” (I agree).
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
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