1. a shrill, whistlelike sound or loud raucous shout made to express disapproval at a theater, meeting, etc.
2. an instrument for producing such a sound.
3. to sound catcalls.
4. to express disapproval of by catcalls.
5. a shrill whistle or cry expressing disapproval, as at a public meeting, etc
6. to utter such a call (at); deride with catcalls