1[in adjectives, nouns, and adverbs] used to say that someone or something is not a particular thing, or does not do a particular thing: non-British visitors a non-smoker (=someone who does not smoke) a nonstop flight (=one in which a plane flies from one place to another without stopping on the way)2[in nouns] used to refer to a situation where a particular action did not happen or will not happen: non-payment of taxes They were very disappointed at his non-appearance (=the fact that he did not go to an event where he was expected).