1. To promise, to give, or to allow something to take place: The supervisor, where Jim was working, vouchsafed that the contract, which he was negotiating, would cost the customers very little.
2. To grant or to give, as by favor, graciousness, or condescension: Shirley decided to vouchsafe a request that was made by her son when he asked if he could go to an afternoon movie.
3. Etymology: from Middle English; "from vouchen sauf, "to vouch or to claim as safe"; from vouchen, "allege, affirm" + sauf, "safe". The one-word form is first recorded in Middle English as fouchesaf in about 1330.