1. The action of pointing out, or making known: "The ringing of the bells at city hall was an indication that the parade had started in the city park."
2. A hint, a suggestion, or a piece of information from which more may be inferred: "Madeline's bemused smile was an indication that she was going to tell a funny joke or story."
3. In medicine, a suggestion or direction as to the treatment of a disease, derived from the symptoms observed: "Doctor Silas suggested that the swollen and tender joint in the patient's thumb was an indication of arthritis."
4. The degree of some physical state, as pressure, temperature, etc., shown by an instrument, as a barometer, anemometer, thermometer, etc.; the reading of a graduated instrument: "The minus 30c on the outdoor thermometer was a clear indication that it was freezing outside."