A can is a metal container, usually cylindrical in shape, which has an airtight seal when it's new. All kinds of goods come in cans, from fruit and vegetables to paint and oil. How to use the modal verbs CAN and COULD in English and the difference between them - Woodward English grammar lesson 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. Can is a modal verb. Can is used to express ability or to say that something is possible. Can is the same for all subjects. We don't add an 'S' in the third person (like other verbs) The verb that comes after Can is in the infinitive without to: I can speak Spanish. (= it is possible for me to speak Spanish = I have the ability to speak Spanish) 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 used instead: Persons under 14 unaccompanied by an adult may not enter. 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 used instead: Persons under 14 unaccompanied by an adult may not enter. Learn about the modal verbs can and could and do the exercises to practise using them. Can and may are most frequently interchangeable in uses indicating possibility; because the possibility of one's doing something may depend on another's compliance, they have also become interchangeable in the sense that means to have permission. We sometimes use be able to instead of can or could for ability. Be able to is possible in all tenses - but can is possible only in the present and could is possible only in the past for ability. You use can, usually in questions, in order to make suggestions or to offer to do something. What can I do around here? This elderly woman was struggling out of the train and I said, Oh, can I help you? .