electroencephalogram Syllabification: (e·lec·tro·en·ceph·a·lo·gram)Pronunciation: /iˌlektrōənˈsefələˌgram/ (abbreviation: EEG)Definition of electroencephalogram noun a test or record of brain activity produced by electroencephalography. electroencephalogram in other Oxford dictionaries Definition of electroencephalogram in the British & World English dictionary