full moon

American  

noun

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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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

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

Based on an island tradition, last celebrated in 1914, it marked the first full moon of February with light, art and torchlit processions.

From BBC • Mar. 29, 2026

If you miss the full moon overnight it will continue to appear nearly full in the few days after the peak.

From BBC • Feb. 1, 2026

These tides typically occur during a new or full moon, causing the oceans to bulge a bit more than usual.

From Los Angeles Times • Dec. 3, 2025

Every full moon, every year until you’re in the ground.

From "The Marrow Thieves" by Cherie Dimaline