Wireless is an old-fashioned term for a radio receiver, referring to its use as a wireless telegraph. The term is widely used to describe modern wireless connections such as wireless broadband internet. 

History

The founding principles and inventions of wireless technology can be found in the lectures and patent record of the electrical engineer Nikola Tesla and in his 1916 deposition on the history of wireless and radio technology, which was earlier pioneered by Jagdish Chandra Bose and Guglielmo Marconi. A wireless set was the radio receiver, referring to its use as a wireless telecommunication station. The term "wireless" was widely used in the UK, long after radio was being used for other signals, such as music.

The British phrase "wireless telegraphy" is one of those which, like aerodrome, was effortlessly transferrable between British and French forces during WWI, but which couldn't quite make it across the Atlantic to become fully accepted into American English. The French equivalent was télégraphie sans fil, which word-for-word translates as "telegraphy without wire." The British abbreviation, used by the military, was W/T. (When voice became transmittable over radio waves, the phrase used in the same era was "radio telephony," whose British abbreviation was R/T.)