arnica
noun [ U ] uk/ˈɑː.nɪk.ə/ us/ˈɑːr.nɪk.ə/
山金车酊（一种萃取自山金车、用于治疗挫伤等的天然药物）
a substance made from a plant, also called arnica, that can be used to treat bruises (= injuries where the skin is dark and sore as a result of being hit by something)