a form of telegraph in which the receiver prints messages typed on the keyboard (like that of a typewriter) of the transmitter: the striking of the keys produces electrical impulses that activate the corresponding keys on the receiver
See teletypewriter in American Heritage Dictionary 4
(tĕlˌĭ-tīpˈrīˌtər)
noun Abbr. TTY or TT
An electromechanical typewriter that either transmits or receives messages coded in electrical signals carried by telegraph or telephone wires.