Other forms: tied the knot; tying the knot; ties the knot
To tie the knot is to get married. Watching two friends tie the knot is one of life's great joys, unless you really hate weddings.
Some historical marriage ceremonies included a ritual where the couple's hands were bound with ribbons or cord — a practice called handfasting — to represent their lives being joined. Whether or not tie the knot refers specifically to this practice, the symbolism is similar. The slang term getting hitched also uses rope imagery, comparing marriage to being tied up, or hitched, to the same wagon. Both expressions draw on the idea of ropes and knots to represent the lifelong commitment of two people joining their paths together.