1.
long sleeves; long-sleeved garment
Sleeves that extend to the wrist, or a garment with such sleeves. Often used as a modifier for shirts, sweaters, and other clothing.
長袖 refers to long sleeves or any garment with long sleeves. It is everyday vocabulary used when discussing clothing choices, especially related to weather or seasons.
Forms
長 (long) + 袖 (sleeve). The same pattern applies to 半袖 (short sleeves, literally "half sleeves").
Common collocations
Usage
Often used without a following noun — 長袖を着る means "to wear something long-sleeved." Common in conversations about weather and seasonal wardrobe changes (衣替え).