noun
neckband; round upright collar
Refers to the round, upright collar found on traditional Japanese garments such as 着物 or 羽織. Not a general term for any neckband.
この着物の上頸は、しっかりと立っている。
The neckband of this kimono stands up firmly.
羽織の上頸をきれいに整える。
I neatly adjust the round collar of the haori.
襟 is the general word for collar or neckline on any garment, while 上頸 specifically refers to the round upright collar on traditional Japanese clothing.
Compound of 上げ (age, 'raised') + 頸 (kubi, 'neck'). The kanji 頸/頚 specifically refers to the neck, and the term describes the raised collar around the neck area.