the crescent-shaped area at the base of the human fingernail
同义词：lunula, lunule
the time at which the moon is at first or last quarter when half its face is illuminated
half-moon详细解释
half-moon n.（名词）The moon when only half its disk is illuminated.半月：月轮只能被看到一半时的月亮Something, such as the lunula of a fingernail, that is shaped like a crescent.半月形的：如半月瓣指甲似的东西，有着新月样的形状
