half-moon half-moon /ˈhæf muːn/

noun

1. () The crescent-shaped area at the base of the human fingernail  ( lunula , lunule , half-moon )
   the crescent-shaped area at the base of the human fingernail
   
2. The time at which the Moon is at first or last quarter when half its face is illuminated  ( half-moon )
   the time at which the Moon is at first or last quarter when half its face is illuminated