Lewis & Short

mansŭētūdo, ĭnis, f. [mansuetus], tameness.

  1. I. Lit. (post-class.): elephanti, Just. 15, 4, 19.
  2. II. Trop.
    1. A. In gen., mildness, gentleness, clemency (class.): uti clementiā ac mansuetudine in aliquem, Caes. B. G. 2, 14: imperii, Cic. Verr. 2, 5, 44, § 114: morum, id. Off. 2, 9, 32: alterum genus orationis lenitatis et mansuetudinis, id. de Or. 2, 49, 200: animorum, id. Off. 2, 4, 15: hostes, Tac. A. 2, 72.
    2. B. In partic., in the times of the emperors, a complimentary title used in addressing them: mansuetudo tua, your clemency or your grace, Eutr. praef. ad Valent. Imp.