actinalyoudaoicibaDictYouDict[actinal 词源字典]
"Designating the part or surface of an echinoderm or other radiate animal which contains the mouth and surrounding organs (as the lower or oral side of a starfish); relating to this part", Mid 19th cent.; earliest use found in Louis Agassiz (1807–1873), zoologist and geologist. From ancient Greek ἀκτῖν-, ἀκτίς ray + -al.[actinal etymology, actinal origin, 英语词源]