on oath

on oath

Bound by a formal promise to tell the complete and honest truth about an event while on the witness stand in a trial. You are on oath as a witness in this trial, so you must answer my questions completely truthfully! Consider your answer carefully—you're still on oath.
See also: oath, on
Farlex Dictionary of Idioms.

on/under ˈoath

(law) having made a formal promise to tell the truth in a court of law: Is she prepared to give evidence on oath? The judge reminded the witness that he was still under oath.
See also: oath, on
Farlex Partner Idioms Dictionary
See also:
  • on/under oath
  • under oath
  • witness
  • witness to
  • be (a) witness to (something)
  • be witness to something
  • be in at the death
  • be in at the death/kill
  • take an oath
  • in at the kill