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English definition of “swear”

swear

verb uk   /sweər/ us    /swer/ (swore, sworn)

swear verb (USE RUDE WORDS)

B2 [I] to use words that are rude or offensive as a way of emphasizing what you mean or as a way of insulting someone or something: It was a real shock, the first time I heard my mother swear. When the taxi driver started to swear at him, he walked off.Swearing and blasphemy

swear verb (PROMISE)

B2 [I or T] to promise or say firmly that you are telling the truth or that you will do something or behave in a particular way: I don't know anything about what happened, I swear (it). [+ (that)] You might find it difficult to believe, but I swear (that) the guy just came up to me and gave me the money.informal She swore blind (= promised definitely) (that) she didn't know what had happened to the money. [+ to infinitive] New gang members must swear to obey the gang leaders at all times. In some countries, witnesses in court have to swear on the Bible. I swore an oath to tell the truth, the whole truth, and nothing but the truth. A few of us knew what was going to happen, but we were sworn to secrecy (= we were made to promise to keep it a secret). I think his birthday is on the 5th, but I wouldn't/couldn't swear to it (= I am not completely certain about it).Making and breaking promises and commitments
(Definition of swear from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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