noun
day
DAY
noun
1
The 24-hour period during which the Earth completes one rotation, from one midnight to the next.
"We spent three days hiking through the mountains."
2
The part of the 24-hour period when it is light outside, as opposed to night.
"She prefers to study during the day rather than at night."
3
The hours spent at work or school.
"He had a long day at the office and just wanted to go home."
4
A particular period or era, especially referring to someone's lifetime or a past time.
"In her grandmother's day, people wrote letters instead of texting."
How to Use Day
Learner’s notesIn plain EnglishOne rotation of the Earth (24 hours), the light part of that period, or — loosely — an era or time in history.
Common pairings
all day
day by day
back in the day
call it a day
Word Forms
dayed past tense, days plural, days singular
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Etymology
From Old English dæg, an ancient Germanic word ultimately traced back to a Proto-Indo-European root meaning "to burn" — likely a reference to the heat and light of the sun.