Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “day”

day

noun [C]    /deɪ/
a period of 24 hours, esp. from 12 o’clock one night to 12 o’clock the next night, or the part of this period after the sun rises but before it goes down, when there is light: My husband picks up our son every day after school. In summer the days are longer and we have cookouts in the backyard. We leave on vacation the day after tomorrow. A day is also the part of a period of 24 hours that you spend at work: He’s been working 12-hour days this week. Days can mean a long period of time: In those days (= that period in history), people had large families.
(Definition of day noun from the Cambridge Academic Content Dictionary © Cambridge University Press)
Focus on the pronunciation of day

Definitions of “day” in other dictionaries

Word of the Day

friendship

a situation in which two people are friends

Word of the Day

Blog

Read our blog about how the English language behaves.

Learn More

New Words

Find words and meanings that have just started to be used in English, and let us know what you think of them.

Learn More