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

“She was born under a full moon in the arms of mother nature. The jaguars taught her to run, the birds to fly,” her intro video intoned.

From Los Angeles Times • Apr. 13, 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

For sky watchers in Asia, Australia and parts of the Americas the full moon will coincide with a rare total lunar eclipse which will make the Moon appear red.

From BBC • Mar. 3, 2026

The first full moon of meteorological spring, also known as the Worm Moon, is set to rise in UK skies on 3 March.

From BBC • Feb. 28, 2026

In the silvery light of the full moon she looked enormous.

From "Jeremy Thatcher, Dragon Hatcher" by Bruce Coville