tongue and groove joint

1. 1.

   a mortise joint made by fitting a projection on the edge of one board into a matching groove on another board

   Broadermortise joint

Questions about tongue and groove joint

What does tongue and groove joint mean?

tongue and groove joint means "a mortise joint made by fitting a projection on the edge of one board into a matching groove on another board".

Is tongue and groove joint a common word?

tongue and groove joint is banded "Rare" — specialist or archaic — most readers will not have met it. The band comes from how often the word appears in a large corpus of everyday English, not from an editor's impression.