noun
tuck at the waist
A sewing technique where fabric is folded and stitched at the waistline to adjust the length or fit of a garment, commonly used in kimono or children's clothing.
子供の着物は、成長に合わせて腰上げをして着せます。
Children's kimono are worn with a tuck at the waist to adjust for growth.
腰上げをほどくと、着物の丈が長くなります。
When you undo the waist tuck, the length of the kimono becomes longer.
肩上げ is a tuck at the shoulders, while 腰上げ is a tuck at the waist. Both are used to adjust garment size, especially for children's kimono.
Compound of 腰 (こし, 'waist') and 上げ (あげ, 'raising' or 'tucking up').