by

Near or next to.

• The mailbox is by the bus stop.

From one side of something to the other, passing close by; past.

• The stream runs by our back door.
• He ran straight by me.

Not later than (the given time); not later than the end of (the given time interval); before.

• Be back by ten o'clock!
• We'll find someone by the end of March.
• I'll have been cycling for longer than two hours by lunchtime.

After a given amount of time has elapsed or a given event has occurred.

• By February, we were all sick of the cold.
• By the time I realized I had left my phone at home, I was already two blocks from work.

Indicates the person or thing that does or causes something: Through the action or presence of. Following a passive verb.

• The matter was decided by the chairman.
• The boat was swamped by the water.
• He was protected by his body armour.

Following a passive verb.

• The matter was decided by the chairman.
• The boat was swamped by the water.
• He was protected by his body armour.

Following a noun.

• There was a call by the unions for a 30% pay rise.

Following an adjective.

• I was aghast by what I saw.

Indicates the creator of a work: Existing through the authorship etc. of.

• There are many well-known plays by William Shakespeare

Indicates a means of achieving something: Involving/using the means of.

• I'd know you anywhere by your gravelly voice.
• I avoided the guards by moving only when they weren't looking.
• By Pythagoras' theorem, we can calculate the length of the hypotenuse.

Indicates an authority according to which something is done.

• By the power vested in me, I now pronounce you man and wife.
• I live by my own code of ethics.
• By Jove! I think she's got it!

Invokes an authority in an oath.

• By Jove! I think she's got it!
• By all that is holy, I'll put an end to this.

Indicates a means of classification or organisation.

• I sorted the items by category.
• Table 1 shows details of our employees broken down by sex and age.

Indicates the amount of change, difference or discrepancy

• Our stock is up by ten percent.
• We won by six goals to three.
• His date of birth was wrong by ten years.

In the formulae X by X and by Xs, indicates a steady progression, one X after another.

• We went through the book page by page.
• We crawled forward by inches.

[with the] Acted on in units of the specified size or measure. (Sometimes hyperbolically)

• sold by the yard; cheaper if bought by the gross
• While sitting listening to the radio by the hour, she can drink brandy by the bucketful!
• He sits listening to the radio by the hour.

Per; with or in proportion to each.

• His health was deteriorating by the day.
• The pickers are paid by the fortnight by the American bushel.

Indicates a referenced source: According to.

• He cheated by his own admission.
• By my reckoning, we should be nearly there.

Along a path which runs past someone or something.

• I watched the parade as it passed by.

In the vicinity, near.

• There was a shepherd close by.

To or at a place, as a residence or place of business.

• I'll stop by on my way home from work.
• We're right near the lifeguard station. Come by before you leave.

Aside, away.

• The women spent much time after harvest putting jams by for winter and spring.

Beyond or past a certain point.

• I'll somehow manage to get by.

Out of the way, off to one side.

• a by path; a by room

Subsidiary, incidental.

• by catch; a by issue

Alternative form of bye.

Dated form of bye (“goodbye”).