绒 is a bound morpheme (b.f.) meaning 'fine hair, down, or soft fabric with a fuzzy surface'. It never stands alone in modern Chinese — you always see it as part of compound words like 天鹅绒 (tiān'éróng, velvet), 绒线 (róngxiàn, knitting wool), 绒毛 (róngmáo, down/fuzz), or 羽绒服 (yǔróngfú, down jacket). The core idea is soft, fine, fuzzy texture, whether from animal hair, plant fibers, or manufactured fabric.