To betroth means to formally promise that two people will marry each other. In many cultures throughout history, parents would betroth their children to someone while they were still young, creating a binding agreement that they would marry when they grew up. A betrothal is more serious than just dating or even being engaged in the modern sense: it was a legal contract, almost as binding as marriage itself.

In medieval Europe, royal families betrothed princes and princesses to form alliances between kingdoms. A king might betroth his daughter to a neighboring prince to secure peace between their nations. In Romeo and Juliet, Juliet's father wants to betroth her to Count Paris, but she's already secretly married to Romeo.

When two people are betrothed, they are called the betrothed. The word sounds old-fashioned because formal betrothals are rare in modern Western society, where people usually choose their own marriage partners. You'll mostly encounter this word in historical fiction, fairy tales, or stories set in the past. Jane Austen's novels, for example, feature characters navigating the complicated rules of courtship and betrothal in 19th-century England.