Definify.com
Webster 1913 Edition
Half-moon
Half′-moonˊ
(-moōnˊ)
, Noun.
 1. 
The moon at the quarters, when half its disk appears illuminated. 
2. 
The shape of a half-moon; a crescent. 
See how in warlike muster they appear,
In rhombs, and wedges, and
In rhombs, and wedges, and
half-moons
, and wings. Milton.
3. 
(Fort.) 
An outwork composed of two faces, forming a salient angle whose gorge resembles a half-moon; – now called a 
ravelin
. 4. 
(Zool.) 
A marine, sparoid, food fish of California (
Caesiosoma Californiense
). The body is ovate, blackish above, blue or gray below. Called also medialuna
. Webster 1828 Edition
Half-moon
H`ALF-MOON
,Noun.
  1.
 Any thing in the shape of a half-moon.  In fortification, an outwork composed of two faces, forming a salient angle, whose gorge is in the form of a crescent or half-moon.Definition 2025
half-moon
half-moon
English
Noun
half-moon (plural half-moons)
- the moon, in its first or last quarter, when only half the face is illuminated
 - anything shaped like a crescent, especially the base of a fingernail
 
Translations
the moon in its first or last quarter
anything shaped like a crescent