Definitions for "canned"
Recorded; in contrast with live; -- used of sound or video broadcasts.
recorded for broadcast; "a transcribed announcement"; "canned laughter"
The term to describe material that is recorded for repeated use on television or radio.
Keywords:  jar, sealed
Sealed in a can or jar.
Keywords:  sms, thumb, template, sort, easily
Canned messages are messages that are already there, sort of like a template, where you don't have to type the same messages over and over again. You can save your thumb some work and insert them quickly and easily into your SMS messages.
Discharged or dismissed from service.
A slang term for a standard "off the shelf" speech or presentation. Often, the term "canned" is used in a negative context to refer to material that a speaker uses too often, without changes, in presentations.