Learner's definition of AT
1 — used to indicate the place where someone or something is
We're staying at a hotel.
The kitchen is at the back of the house.
He was sitting at the table.
They left for Cambridge early and arrived at [=in] Cambridge before noon.
The party will be at Susan's house. = The party will be at Susan's.
Ann works at [=in] a library.
We met at a party.
They live at opposite ends of town.
They met at [=on] a street corner in a town.
“Is your father at home?” [=is your father home?] “No, he's working late at the office.”
She met us at the door.
He was standing at [=next to] the window.
There were 200 people at the wedding. [=200 people attended the wedding]
Their older son has graduated, but their younger son is still at school. [=is still attending school]
Who was at the controls when the accident occurred?
2 — used to indicate the person or thing toward which an action, motion, or feeling is directed or aimed
She pointed her gun at the target.
He's angry at his brother.
His anger is directed at his brother.
She shouted (words of) abuse at me.
He looked directly at me.
They laughed at him.
She grabbed at my arm. [=she tried to grab my arm]
He poked at his food.
3 — used to indicate something that is being tried or attempted 4 : because of or in reaction to (something) — used to indicate the cause of an action, feeling, etc.
I was greatly surprised at [=by] the result. [=the result surprised me greatly]
He enlisted in the army at his father's urging. [=because his father urged him to]
She visited the museum at my suggestion.
They came here at our invitation.
You can act at your own discretion.
5 — used to indicate an activity
He's very serious when he's at work. [=when he's working]
children who are at play [=children who are playing]
She's good at (playing) chess. [=she plays chess well]
I'm bad at cooking. [=I'm a bad cook, I do not cook well]
She's doing very well at her studies.
6 — used to indicate a situation or condition 7 a — used to indicate position on a scale or in a series b — used to indicate a rate 8 — used to indicate an age or time
He plans to retire at (age) 65.
He called us at (about/exactly) 9 o'clock on July 24.
I still think of her at certain moments/times.
He was president of the company at (the time of) his death.
9 — used to indicate the method by which something is done 10 a — used in phrases like at best, at worst, etc., to indicate a possible result or condition that is considered best, worst, etc.
b — used in phrases like at its best, at its worst, etc., to indicate that something or someone is as good, bad, etc., as possible
The company will make a small profit at best this year. [=it is not possible that the company will earn anything better/more than a small profit]
We might be 5 or 10 minutes late at worst. [=we will not be more than 5 or 10 minutes late]
We should arrive by noon at the latest. [=we should not arrive later than noon]
◊ The word at is used in speech in e-mail addresses.
In writing, the symbol @ is used instead.
: doing some activity
I didn't expect her to have started working yet, but she was already (hard) at it when I arrived. [=she was already working (hard) when I arrived]
My neighbors are always arguing, and they were at it again last night. [=they were arguing again last night]
Since we're cleaning the kitchen, we should wash the floor while we're at it. [=we should wash the floor when we clean the kitchen]
“I'm going to the store to buy a newspaper.” “While you're at it, could you get some milk?”