The moon when only half its disk is illuminated.(noun)
Something, such as the lunula of a fingernail, that is shaped like a crescent.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "half-moon" in a sentence
"moon is 50 percent illuminated at its First or Last Quarter phase; also sometimes called the "half-moon", that it would be shining only half as bright as a full moon."
"Cal eyed the window through his half-moon reading glasses."
"No need to see the faded green wallpaper, the tired carpet, the half-moon telephone table, and the coat-stand in the hallway."