[on and off] See: [OFF AND ON].

[on approval] {adv. phr.} With the understanding that the thing may […]

[on behalf of] See: [IN BEHALF OP].

[on board] (1) {prep.} On (a ship). * /Joan was not […]

[on board] (2) {adv.} or {adj. phr.} On a ship. * […]

[on borrowed time] See: [LIVE ON BORROWED TIME].

[on call] {adj. phr.} 1. Having to be paid on demand. […]

[on cloud nine] {adj. phr.}, {slang} Too happy to think of […]

[on condition that] {conj.} Providing that; if. * /I will lend […]

[on deck] {adv.} or {adj. phr.} 1. On a floor of […]