Medical Definition of ANODE. 1. : the electrode of an electrochemical cell at which oxidation occurs: as a: the positive terminal of an electrolytic cell b: the negative terminal of a storage battery that is delivering current.2. : the electron-collecting electrode of an electron tube—compare cathode.ull Definition of ANODE. 1. : the electrode of an electrochemical cell at which oxidation occurs: as a: the positive terminal of an electrolytic cell b: the negative terminal of a galvanic cell. 2.