ichidan verb, transitive verb
ease (sewing); shirr
Sewing term: to gather or ease fabric slightly, often to fit a sleeve or curved seam. 'Shirr' is a less common English equivalent.
袖のカーブに合わせて、袖山をいせる。
Ease the sleeve cap to fit the armhole curve.
この生地は伸びないので、いせて縫
This fabric doesn't stretch, so you need to ease it in when sewing.