click (v.) Look up click at Dictionary.com
1580s, of imitative origin (cf. Dutch and East Frisian klikken "to click; Old French clique "tick of a clock"). The figurative sense of "fit together" (based on the sound of a key in a lock, etc.) first recorded 1915. Related: Clicked; clicking.
click (n.) Look up click at Dictionary.com
1610s, from click (v.).