Archaic word for 'sleeve', found mainly in classical literature. In modern Japanese, 袖 (そで) is the standard term.
In an old poem, it is written, 'Tears fall upon my sleeve.'
Compound of 衣 (ころも, 'garment') and 手 (て, 'hand'), with rendaku voicing of て to で. The exact historical derivation is uncertain, but the word is attested in classical Japanese.