SWEAR

(PROMISE) [verb] [past simple] swore, [past participle] sworn - to state or promise that you are telling the truth or that you will do something or behave in a particular wayI don't know anything about what happened, I swear. [I]You might find it difficult to believe, but I swear (that) the guy just came up to me and gave me the money. [+ (that) clause]New gang members must swear to obey the gang leaders at all times. [+ to infinitive]In some countries, witnesses in court have to swear on the Bible. [I]I swore an oath to tell the truth, the whole truth and nothing but the truth. [T]When someone is sworn in, they make a formal promise to be honest or loyal, either because they are in a law court or because they are starting a new official job.The next witness was sworn in. [M]William Jefferson Clinton was sworn in as the 42nd President of the United States of America. [M]A few of us knew what was going to happen, but we were sworn to secrecy (= we were forced to promise that we would keep it a secret). [T](informal) I think his birthday is on the 5th, but I wouldn't/couldn't swear to it (= I am not completely certain about it). [I](esp. UK informal) She swore blind (= emphasized that it was true) (that) she didn't know what had happened to the money.(informal) My dad swears by (= believes in the effectiveness of) these vitamin pills.