- an edible fish, Medialuna californiensis, found in southern California, having a slate-gray body.
- the moon when, at either quadrature, half its disk is illuminated.
- the phase of the moon at this time.
- something having the shape of a half-moon or crescent.
- the moon at first or last quarter when half its face is illuminated
- the time at which a half-moon occurs
- something shaped like a half-moon
- (as modifier)half-moon spectacles
- anatomy a nontechnical name for lunula