What is Audiendo Et Terminando?

Legal Definition
Oyer and terminer, English crim. law. A writ, or rather a commission, directed to certain persons for the trial and punishment of such persons as have been concerned in a riotous assembly, insurrection or other heinous misdemeanor.
-- Bouviers Law Dictionary
Legal Definition
A writ or commission to certain persons to appease and punish any insurrection or great riot. Fitzh. Nat. Brev. 110.
-- Black's Law Dictionary
Legal Definition
-- Ballentine's Law Dictionary