noun
slicing a fish down the back
A fish preparation technique where the fish is cut open along the back, often used for grilling or drying.
アジを背割りにして干物を作る。
I slice the horse mackerel down the back to make dried fish.
noun
slit in the back of a garment
A vertical opening at the back of clothing, such as a jacket or dress, for ease of movement or design.
このジャケットは背割りが深く入っている。
This jacket has a deep slit in the back.
noun
split in lumber to prevent cracking
A deliberate cut made in a piece of wood to relieve stress and reduce the chance of splitting during drying.
木材の背割りは乾燥時の割れを防ぐために入れる。
A split is made in the lumber to prevent cracking during drying.
Compound of 背 (se, 'back') and 割り (wari, 'split, cut'). The exact historical derivation is uncertain, but the word transparently describes a cut or split made along the back of something.