Definition of halfmoon:
(n) :
A species of sea chub, Medialuna californiensis, native to the Pacific coast of North America.
(n) :
(biology) Any of certain fish in the subfamily Scorpidinae, such as:
(n) :
A town in Saratoga County, New York.
(n) :
A township in Centre County, Pennsylvania.
(n) :
A place in the United States:
(n) :
Alternative form of half-moon. [The moon in its first or last quarter when only half the visible face is illuminated; a quarter moon.]