Longman Dictionary of Contemporary English - at

~ prep 1 used to show a point in space where someone or something is, or where an event is happening  (We'll meet at my house. | a huge queue at the bus stop. | They sat down at a corner table. | at Jack's/Sue's etc (=at Jack's house, Sue's house etc))  (Pete's round at Mel's.) at the doctor's/the bank/the airport etc (=at a place you go to for a particular purpose)  (Guess who I met at the dentist's?) 2 at a party/club/funeral etc at an event while it is taking place  (I met my wife at a disco. | They're all out at the cinema.) 3 at school/work etc regularly going to school, work etc  (Is Jessica still at school? (=does she go to school regularly)) 4 at lunch/dinner etc eating your lunch, dinner etc  (I'm sorry, Pam's at lunch just now.) 5 used to show an exact time  (The film starts at 8 o'clock. | at the moment (=now))  (We're really busy at the moment.) 6 used to show a particular period of time during which something happens  (My husband often works at night. | We like to go to Midnight Mass at Christmas.) 7 used to show the person or thing that an action is directed or aimed at  (Protesters threw rotten eggs at the speakers. | Jake shot at the deer but missed. | Look at that! | Stop shouting at the kids all the time.) 8 used to show the thing that caused an action or feeling  (The children all laughed at his jokes. | I'm surprised at you! | Dad got really mad at me for scratching the car.) 9 used to show the subject or activity that you are considering when making a judgment about someone's ability  (Barbara's getting on really well at her new job. | Rosa's a genius at chemistry. | good/bad etc at (doing) sth)  (Luis was always good at maths. | Matt's bad at handling people.) 10 used to show a continuous state or activity  (two nations at war | Many children are still at risk from neglect or abuse. | Granny's at peace now (=dead) | at large (=if someone or something dangerous is at large they are in a particular area and may harm or kill someone))  (rumours of a black panther at large) 11 used to show a price, rate, level, age, speed etc  (old books selling at 10 cents each | The house was sold at a price of $250,000. | You should have more sense at your age. | The car was going at about 50 mph. | Amanda rode off at a gallop.) 12 at least/worst/most etc the least, worst etc thing possible  (John has to practise for at least half an hour every day. | At worst, up to 50% of the population could be affected. | at the very least/most/worst etc)  (That car's worth $250 at the very most. | at its/her/their best etc)  (The garden is at its best in June. | This was Sampras at his most powerful.) 13 used to show that you are trying to do something but are not succeeding or completing it  (George was just picking at his food. | Sarah took another sip at her wine. | I clutched at the rope but missed.) 14 at sb's invitation/command because someone asks or orders you to do something  (Rachel attended the dinner at the chairman's command.) 15 at that a) also or besides  (It's a new idea, and a good one, at that.) b) after something happens or as a result of it; then  (Tess called him a liar and at that he stormed out of the room.)  (- see also leave it at that leave1 (12)) 16 at a time at the same time  (Ben was putting chocolates in his mouth two at a time.) 17 where it's at informal used to describe a place or activity that is very popular, exciting, and fashionable  (This Hacienda Club is where it's at.)  (- see also (not) at all all3)