Cathodal closure contraction refers to the involuntary muscle twitch that occurs upon applying an electric current to the cathode of an electrode. Synonymous terms for cathodal closure contraction include cathodal contraction, cathodic twitch, and cathodal refractory contraction. All these terms describe the same phenomenon: the contraction of muscles in response to the stimulation of the cathode with electric current. These synonyms are widely used in the field of neurophysiology and are essential to understand and discuss the physiological processes associated with the application of electrical currents. An awareness of these synonymous terms allows for effective communication and comprehension among researchers, clinicians, and scholars studying muscle physiology and electrotherapy.