on

preposition (PROCESS)

/ɒn/

/ɑːn/

Definition

› used to show that a condition or process is being experienced: He accidentally set his bed on fire. Their flights to Paris are on special offer at the moment. Martin's on holiday this week. I'll be away on a training course next week. I often feel carsick when I'm on a long journey. Crime is on the increase (= is increasing) again.

(Definition of on preposition (PROCESS) from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)