Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

  

English definition of “by”

by

preposition (NOT LATER THAN)    /baɪ/
A2 not later than; at or before: She had promised to be back by five o'clock. The application must be in by the 31st to be accepted. By the time I got to the station the train had already gone.Before, after and alreadyAfter and behind Grammar:Before, by, till, untilIf you have to do something before a certain point in time, then when that point arrives, the action must already be completed:See moreGrammar:ByBy is a preposition or an adverb.See moreGrammar:By and timeWe use by meaning ‘not later than’ to refer to arrangements and deadlines:See moreGrammar:By and the passiveWhen we use the passive voice, we can use a phrase with by to say who did the action:See moreGrammar:By meaning ‘how to do something’We use by + -ing form to describe how to do something:See moreGrammar:By + myself etc.When we say by + myself, yourself, himself, herself, itself, oneself, ourselves, yourselves, themselves, it means ‘alone’. We sometimes use all for emphasis:See moreGrammar:By and placeWe use by to mean ‘beside’ or ‘at the side of’:See moreGrammar:By and measurements and amountsWe use by to talk about measurements, and increases and decreases in amounts:See moreGrammar:By meaning ‘during’We sometimes use by + day and by + night to mean ‘during the day or the night’:See moreGrammar:By meaning ‘written’ or ‘composed’We use by when we talk about the writers of books, songs, poems, symphonies, etc.:See moreGrammar:By: typical errorsSee more
(Definition of by preposition (NOT LATER THAN) from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)
Focus on the pronunciation of by

Definitions of “by” in other dictionaries

Word of the Day

work out

to exercise in order to improve the strength or appearance of your body

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