Adjective
That is either fully on or fully off, and is used to toggle a status between on and off; as in an on-off switch
John loved being with his sister, but from time to time he wished she had an on-off switch.
(of a relationship) Synonym of on-again, off-again
Source: en.wiktionary.org1951–1959 After much personal struggle and a turbulent on-off engagement, he married the Chilean-born American actress Felicia Cohn Montealegre on September 10, 1951. Source: Internet
Because Morse code transmissions employ an on-off keyed radio signal, it requires less complex transmission equipment than other forms of radio communication. Source: Internet
For digital modulation schemes it has been shown that for properly implemented on-off keying amplitude-shift keying systems, co-channel rejection can be better than for frequency-shift keying systems. Source: Internet
Elliot and J.D. were the appointed on-off couple of this series, and they were a good fit for each other, despite how typically badly they may have treated each other. Source: Internet
An Exception: High-frequency (HF) transceiver equipment is normally not designed with an interlock between receiver squelch and transmitter on-off key. Source: Internet
Harry’s longest-running romance was with Chelsy Davy, who had a six-year, on-off relationship with the Prince between 2004 and 2011. Source: Internet