In Electrochemistry the cathode is the electrode where the reduction reaction occurs.
In an electrolytic cell, the cathode is where the negative polarity is applied. Common results of reduction at the cathode are hydrogen gas or pure metal from metal ions.
The term derives from the Greek “kathodos” (1834 - William Whewell) implying “way down,” thus indicating the direction (down) into the cell (or other devices) that electrons move.