full moon

American  

noun

full moons plural

1. the moon when the whole of its disk is illuminated, occurring when in opposition to the sun.

2. the phase of the moon at this time.

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full moon British  

noun

1. one of the four phases of the moon, occurring when the earth lies between the sun and the moon so that the moon is visible as a fully illuminated disc

2. the moon in this phase

3. the time at which this occurs

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full moon Scientific  

/ fl /

1. The phase of the Moon in which it is visible as a fully illuminated disk. This phase occurs when the Moon is on the opposite side of Earth as the Sun and is not in Earth's shadow.

2. See more at moon Compare new moon

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Other Word Forms

Noun Inflected Forms

• full moons
  plural

Etymology

Origin of full moon

before 1000; Middle English ful moyne, Old English fulles monan

Compare meaning

How does full-moon compare to similar and commonly confused words? Explore the most common comparisons:

• new moon vs. full moon

Example Sentences

The shot of the battered Big Baby, one eyelid drooping, sitting on a swing gazing at the full moon, is far more chilling than anything in the “M3GAN” movies.

From Los Angeles Times • Jun. 17, 2026

The troops are requisitioned, the destroyers in place, the full moon just right, the secrecy of the invasion delicate.

From Los Angeles Times • May 29, 2026

The term - a bomber's moon - refers to a bright full moon during World War Two that illuminated the landscape almost like daylight, making it easier for aircrews to navigate and strike their targets.

From BBC • Apr. 14, 2026

This ensures the holiday lands on the first Sunday after the first full moon occurring on or after the spring equinox.

From Barron's • Apr. 2, 2026

In Elberon the night before, under nearly a full moon, hundreds of railroad workers had toiled in the oppressive heat.

From "Ambushed!" by Gail Jarrow