first quarter

noun

Astronomy.

1. the instant, approximately one week after a new moon, when one half of the moon's disk is illuminated by the sun.

first quarter

noun

1. one of the four principal phases of the moon, occurring between new moon and full moon, when half of the lighted surface is visible from earth Compare last quarter

Word History and Origins

Origin of first quarter¹

First recorded in 1905–10

Example Sentences

The consultation process began on Monday, and is expected to end in the first quarter of next year.

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The transaction is expected to close in the first quarter of 2026.

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Players responded by piling on a season-high 46 points in the first quarter.

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Oil jumped after OPEC+ confirmed it will stick with plans to pause production hikes during the first quarter, citing lower seasonal demand.

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OPEC+ confirmed a pause on oil production hikes for the first quarter of 2026 due to expected weaker market conditions.

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