- under oath
or on oath also upon oath
: under the solemn obligation of an oath
was under oath to tell all he knew
* * *having sworn to tell the truth, esp. in a court of law
* * *under oath (also on oath)law : having made a formal promise to tell the truth in a court of law
In a U.S. court of law, a witness must swear under oath to tell “the truth, the whole truth, and nothing but the truth.”
He said in testimony given under oath that he was not there the night of the crime.• • •Main Entry: ↑oath
* * *on/under ˈoath idiom(law) having made a formal promise to tell the truth in court
Is she prepared to give evidence on oath?
The judge reminded the witness that he was still under oath.
You have sworn under oath that you never met this man.Main entry: ↑oathidiom
Useful english dictionary. 2012.