A betrothal is an engagement, a promise to marry. If you want to sound fancy when you’re about to get married, just mention your betrothal, preferably to a duke or duchess.
This 19th century word has roots meaning “faith” or “constancy,” and those meanings still hold — a betrothal is a promise to remain faithful and constant by getting married. A betrothal is basically a fancy word for an engagement. This word is slightly old-fashioned, and it also has an official, sophisticated flavor to it. After a proposal has been accepted, a couple will announce their betrothal to their friends and family. The couple is then betrothed to each other.