1. An automatic frequency analysis of the constituent wave forms of the electroencephalogram or a graphic record of the electrical activity of the brain as recorded by an electroencephalograph or an instrument for recording the electrical activity of the brain, usually by means of electrodes placed on the scalp; used to diagnose tumors of the brain, to study brain waves, etc.
2. The recording, study, and interpretation of electroencephalographic wave patterns or a technique for recording electrical activity in the brain, whose cells emit distinct patterns of rhythmic electrical impulses.