1620s, "action of touching," from Latin contactus "a touching," from past participle of contingere "to touch, seize," from com- "together" (see com-) + tangere "to touch" (see tangent).
Figurative sense of "connection, communication" is from 1818. As a signal to the person about to spin an aircraft propeller that the ignition is switched on, the word was in use by 1913. Contact lens is first recorded 1888; short form contact is from 1961.