noun
stand-up collar; mandarin collar
A stiff, close-fitting collar that stands up around the neck, typical of Japanese school uniforms (gakuran) and some military-style jackets.
彼は詰襟の学生服を着ている。
He is wearing a school uniform with a stand-up collar.
詰襟のシャツはフォーマルな印象を与える。
A shirt with a mandarin collar gives a formal impression.
Compound of 詰め (tsume, 'stuffing' or 'close-fitting') and 襟 (eri, 'collar'). The kanji 詰 carries the sense of being packed tightly, describing the collar's snug fit.