Definitions of caller:

• noun:   a social or business visitor
• noun:   the person initiating a telephone call

  Example: "There were so many callers that he finally disconnected the telephone"

• noun:   the person who convenes a meeting

  Example: "Who is the caller of this meeting?"

• noun:   someone who proclaims or summons in a loud voice

  Example: "The callers were mothers summoning their children home for dinner"

• noun:   a person who announces the changes of steps during a dance

  Example: "You need a fiddler and a caller for country dancing"

• noun:   the bettor in a card game who matches the bet and calls for a show of hands
• noun:   an investor who buys a call option
• adjective:   providing coolness

  Example: "`caller' is a Scottish term as in `a caller breeze'"

• adjective:   fresh

  Example: "Caller fish"

• name:  A surname (very rare: popularity rank in the U.S.: #74419)