Definition of caller id:
(n) :
(countable) The telephone number and/or name of the originator of an incoming telephone call, displayed on the screen of the telephone or other electronic device receiving the call.
(n) :
(uncountable) The service of providing such information, sometimes included in one's standard telephone contract and sometimes available for an extra fee.
(n) :
Alternative form of caller ID. [(countable) The telephone number and/or name of the originator of an incoming telephone call, displayed on the screen of the telephone or other electronic device receiving the call.]