マチ

noun

gusset; crotch piece

A piece of fabric inserted into a garment to add room or shape, especially in the crotch of pants or underarms. Common in sewing and tailoring contexts.

• このパンツにはマチが付ついているので動うごきやすい。

  These pants have a gusset, so they're easy to move in.

• 袖そでの下したにマチを入いれると腕うでが上あげやすくなる。

  Inserting a gusset under the sleeve makes it easier to raise your arm.