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Definition of halfmoon

halfmoon

/ˈhæfˌmuːn/
Plural:halfmoons
•
Adjective:half-moon
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halfmoon Lexical Profile

• noun

1

The moon when exactly half of its disk appears illuminated by the sun.

Example

"A bright halfmoon hung in the clear autumn sky, casting a pale glow over the silent forest."


2

A semicircular or crescent-shaped object, architectural feature, or arrangement.

Example

"The architect designed a beautiful stone patio in the shape of a halfmoon facing the garden."


3

A marine fish (Medialuna californiensis) native to the Pacific coast of North America, or a popular domestic breed of Betta fish characterized by a tail fin that flares to a full 180-degree semicircle.

Example

"The aquarist proudly displayed a striking blue halfmoon, its tail flaring perfectly as it swam around the planted tank."

Synonyms
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Antonyms
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Word Nuance & Usage

Often hyphenated as 'half-moon' when referring to the lunar phase or a semicircular shape, while the unhyphenated compound 'halfmoon' is frequently used in biology to name specific fish, such as the halfmoon betta.

Word Origin & Etymology

A compound of the Old English words 'healf' (half) and 'mōna' (moon), historically used to describe the lunar phase and subsequently applied to semicircular shapes and specific animals.

Usage Trend

Historical frequency of usage in published text.

180019102020

Cite this Entry


Wordmom. (2026). Definition of Halfmoon. In Wordmom Dictionary. Retrieved Nov 5, 2026, from https://wordmom.com/dictionary/halfmoon
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