Tie the knot Informal

To get married.

It’s typically used in a light, informal, or celebratory tone rather than in formal or legal contexts.

The phrase is often said to derive from an ancient Celtic handfasting ceremony, in which the hands of a couple being betrothed or married were literally bound together with a cord or ribbon, symbolizing their union — a custom associated with both pre-Christian Celtic tradition and later Scottish folk practice, and still revived today in some neo-pagan and Wiccan wedding ceremonies. That said, the specific historical link between this ritual and the English idiom’s coinage is not rigorously documented; what is better established is that “knot” became symbolic of the bond of marriage in English by the early 13th century, well before the specific phrase “tie the knot” is attested, so the wedding association of knots and binding likely built up gradually in the language rather than being borrowed wholesale from a single ceremony.

They finally tied the knot after being together for ten years.

My sister is tying the knot next summer.

The couple tied the knot in a small ceremony on the beach.

A: Did you hear Anna and Marco are engaged? B: Yes, they’re tying the knot in June.