Meaning of “by” - Learner’s Dictionary

by

preposition uk us strong /baɪ/ weak /, /
DO

A2 used to show the person or thing that does something:

She was examined by a doctor.
The building had been destroyed by fire.
a painting by Van Gogh
HOW

A2 through doing or using something:

Can I pay by cheque?
I sent it by email.
We'll get there by car.
[ + doing sth ] Open the file by clicking on the icon.
HOLDING

B2 holding a particular part of someone or something:

She grabbed me by the arm.
NEAR

B1 near or next to something or someone:

I'll meet you by the post office.
A small child stood by her side.
NOT LATER

A2 not later than a particular time or date:

Applications have to be in by the 31st.
ACCORDING TO

according to:

By law you must be eighteen to purchase alcohol.
PAST

past:

He sped by me on a motorcycle.
AMOUNT

used to show measurements or amounts:

twelve by ten metres of floor space
Interest rates have been increased by 0.25%.
I'm paid by the hour.
Copies have sold by the million.
by accident/chance/mistake, etc

B1 as a result of an accident/chance/mistake, etc:

I went to the wrong room by mistake.
by day/night

during the day/night

day by day/little by little/one by one, etc

used in particular phrases to mean 'gradually' or 'in units of':

Day by day he grew stronger.

(Definition of “by preposition” from the Cambridge Learner’s Dictionary © Cambridge University Press)