Overview

Can is a common English word with several distinct senses: most prominently a modal auxiliary verb expressing ability, permission, possibility or request; a noun denoting a cylindrical metal or tin container used for food and drink; a verb meaning to preserve food in such containers or to dismiss someone; and a variety of slang and acronym uses. Its meaning is determined by context and grammatical role.

As a modal verb

As an auxiliary, can indicates ability (She can swim), permission (Can I leave?), informal request (Can you pass the salt?), or general possibility (It can get cold here). Its past form is could, which also serves for polite requests and hypothetical situations. Unlike ordinary verbs, can has no infinitive (we use "be able to" instead), no participle, and does not take an -s in the third person singular.

The noun can refers to a sealed, typically cylindrical container made from metal (often steel or aluminum) used for packaging foods, drinks and other goods. To can something is to pack and seal it in such a container for preservation. Canned food and canned goods are staples of long-term storage and commercial food distribution. Colloquially, canned or "in the can" can also mean prerecorded or finished, as in a film that is completed.

Slang and idioms

  • To can (slang): to fire someone or terminate employment (They canned him).
  • The can: informal term for a toilet or a jail cell in some varieties of English.
  • Canned: also used to describe formulaic or unoriginal material (a canned response).

Other notable uses

CAN in all capitals commonly refers to Controller Area Network (CAN bus), a robust serial communication protocol widely used in automotive and industrial systems to allow microcontrollers and devices to communicate without a host computer. Can is also the name of an influential German experimental rock band from the 1960s–70s.

Distinctions and usage notes

Writers often distinguish can from may when contrasting ability and permission: may traditionally signals permission or possibility while can signals ability, though modern usage overlaps and native speakers frequently use can to ask for permission. For past ability in specific situations, "was/were able to" is often preferred to clarify meaning (She was able to finish the test).