Esposo/sa: Voz patrimonial del latín sponsus ‘prometido’, participio de spondere ‘prometer’; a lo largo de la historia del español ha pasado de ‘prometido’ a ‘persona que ha contraído esponsales’.

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Both terms share the same etymological root. They come from the latin term spondere (to promise). According to Larousse's dictionary:Hence it's the association with the bond between spouses that passed to the termmeaning handcuffs.