The use of can to ask or grant permission has been common since the 19th century and is well established, although some feel may is more appropriate in formal contexts. May is relatively rare in … Can is usually used in standard spoken English when asking for permission. It is acceptable in most forms of written English, although in very formal writing, such as official instructions, may is often … You use can to indicate that someone is allowed to do something. You use cannot or can't to indicate that someone is not allowed to do something. Can I really have your jeans when you go? We can't … used to say that it is possible for somebody/something to do something, or for something to happen. Can you call back tomorrow? He couldn't answer the question. The stadium can be … Define can. can synonyms, can pronunciation, can translation, English dictionary definition of can. to be able to, have the power or skill to: I can take a bus to the airport. Used to indicate possibility or probability. I wonder if my long lost neighbor can still be alive. Such things can and do happen. "Can" is one of the most commonly used modal verbs in English.