pineal
noun [ C ] uk/ˈpɪn.i.əl/ us/ˈpɪn.i.əl/ (also pineal gland, /ˈpɪn.i.əl ˌɡlænd/ /ˈpɪn.i.əl ˌɡlænd/)
anatomy specialized （大脑中的）松果体an organ in the brain that produces a hormone called melatonin
The pineal produces its hormone melatonin only during the dark. 松果体只在夜间产生褪黑激素。