melatoninWiktionary 原文构词拆分mela-前缀black; dark+tone词根/词干+-in后缀(biochemistry) Used, as a modification of -ine, to form the names of a variety of types of compound; examples include proteins (globulin), carbohydrates (dextrin), dyes (alizarin) and others (vanillin).演变路径（由近及远）英语源自 ←古希腊语 μέλας “black, dark”词源说明From mela- + tone + -in, ultimately from Ancient Greek μέλας (mélas, “black, dark”).释义（英文）名词 NounA hormone, related to serotonin, that is secreted by the pineal gland, and stimulates colour change in the skin of reptiles, and is involved