noun
half lap joint between parallel boards
A woodworking joint where the edges of two parallel boards are notched to overlap, creating a flush surface. Technical carpentry term.
床板をあいじゃくりで接合すると、隙間ができにくい。
When you join floorboards with a half lap joint, gaps are less likely to appear.
この棚の側板は相決りで組まれている。
The side panels of this shelf are assembled with half lap joints.
Compound of 相 (ai, 'mutual') and 決り (jakuri, 'notch, groove'), referring to the interlocking nature of the joint. The exact historical derivation is uncertain, but the term is established in traditional Japanese carpentry.