Final answer:
The abbreviation for electroencephalogram is EEG, which measures brain's electrical activity, whereas ECG or EKG is used for the heart's electrical signals.
Step-by-step explanation:
The abbreviation for electroencephalogram is EEG. An electroencephalogram is a test that measures and records the electrical activity of the brain. Unlike the electrocardiogram, which is abbreviated as ECG or sometimes EKG (with the K coming from the German term "kardiologie"), EEG is specific to brain activity, whereas the ECG/EKG is a recording of the heart's electrical activity, used to diagnose heart function and issues.