What are boards that are shaped to form a tongue-and-groove joint at the edge called?

The term for boards that are specifically shaped to create a tongue-and-groove joint at the edge is referred to as matched lumber. This construction technique involves machining the edges of the boards so that one board has a protruding tongue, while the other has a corresponding groove. When the boards are joined, the tongue fits securely into the groove, creating a tight, seamless connection. This design not only enhances the aesthetic appeal of the finished surface but also helps in minimizing gaps and improving the stability and strength of the assembly.

Matched lumber is commonly used in various applications such as flooring, paneling, and ceiling installations because it allows for easier assembly and a more finished look. This joint is effective in accommodating expansion and contraction of wood, which can occur due to changes in humidity and temperature.