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SESK: Stuff Everyone Should Know · sesk.info/wood-mortise-and-tenon

In a mortise and tenon joint, what is the mortise?

The slot cut to receive the tenon.

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  1. The projecting tongue on the end of a rail
  2. A wooden pin that locks the joint
  3. The slot or hole that receives the tenon ✔

Why: The tenon is the tongue left by cutting away wood around it, and the mortise is the slot it fits into. Kreg calls it one of the strongest and most reliable joints for furniture.

Huh, didn't know that: Traditional timber frames join timbers larger than 5 by 5 inches with hand-cut joints such as mortise and tenon.

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References

Answer: The slot or hole that receives the tenon. The tenon is the tongue left by cutting away wood around it, and the mortise is the slot it fits into. Kreg calls it one of the strongest and most reliable joints for furniture.

  1. Wood Handbook: Wood as an Engineering Material, FPL-GTR-282 (USDA Forest Products Laboratory, 2021) research.fs.usda.gov/treesearch/62200
    A slot cut into a board, plank, or timber, usually edgewise, to receive the tenon
    Checked 2026-10-10.
  2. Wood Handbook: Wood as an Engineering Material, FPL-GTR-282 (USDA Forest Products Laboratory, 2021) research.fs.usda.gov/treesearch/62200
    A projecting member left by cutting away the wood around it for insertion into a mortise to make a joint.
    Checked 2026-10-10.
  3. 9 Types of Wood Joints (Kreg Tool) learn.kregtool.com/learn/joining-wood
    Considered one of the strongest and most reliable joints.
    Checked 2026-10-10.

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