noun
top crease of a sleeve (traditional Japanese clothing)
Refers to the raised seam or crease at the shoulder end of a sleeve in kimono, yukata, and similar garments.
着物の袖山がきれいに決まっている。
The top crease of the kimono sleeve is neatly set.
noun
sleeve cap (Western clothing)
In tailoring, the curved upper part of a set-in sleeve that joins the armhole; a technical term.
このジャケットは袖山のいせ込みが足りない。
This jacket doesn't have enough ease in the sleeve cap.