1520s, distributer (Latinized form is from 1570s), "one who or that which distributes," agent noun from Latin distribuere "to divide, deal out in portions" (see distribute). As a part that passes current in turn to each spark plug in an internal combustion engine, by 1866.
"wires collectively," 1809, later especially "electrical wirework" (1887), from present participle of wire (v.).
1550s, "occurring or acting by turns, one after the other," present-participle adjective from alternate (v.). Electrical alternating current is recorded from 1839, an electrical current which flows alternately in opposite directions without interruption.