n. (also kathode) Electr. 1 the negative electrode in an electrolytic cell or electronic valve or tube. 2 the positive terminal of a primary cell such as a battery (opp. ANODE). cathode ray a beam of electrons emitted from the cathode of a high-vacuum tube. cathode-ray tube a high-vacuum tube in which cathode rays produce a luminous image on a fluorescent screen. °Abbr.: CRT. cathodal adj. cathodic adj.
[ Gk kathodos descent f. kata down + hodos way ]