Definition from Wiktionary, the free dictionary
Extension of roger for received in radio traffic (by 1950), the pronoun referring to the last information received; in use by 1969, popularised at first by radio transmissions from NASA's Apollo missions, later in military fiction.
- (radio telecommunications) Received (used in radio communications to acknowledge that a message has been received and understood)
- 1969 "Capsule Communicator: '11, this is Houston. We've completed the trunnion zero bias setting. You can retrieve the computer and go to BLOCK.' Commander (Neil A. Armstrong): 'Roger that. Thank you.' ", Apollo 11 Air-to-Ground Voice Transcription (Tape 4/5, mission time 5h 16 min), 16 July 1969.
- 1974 "This is the book for everybody who ever groaned under the onslaught of trivia transmitted by the astronauts ('This sunset is really something, Houston...' 'Roger that...'). review of M. Collins, "Carrying the Fire", Flying Magazine, November 1974, p. 108.
- 1989 "'It's going to blow visibility to shit, too.' 'Roger that.'" Tom Clancy, Clear and Present Danger, p. 506.
- (idiomatic) Used to acknowledge receipt and understanding of a message