Lewis & Short

apprŏbātĭo (adp-), ōnis, f. [approbo].

  1. I. An approving, allowing, assenting to, approbation, acquiescence (most freq. in Cic.): id volgi adsensu et populari approbatione judicari solet, Cic. Brut. 49, 185: id. Tusc. 2, 1, 3: hoc decorum movet adprobationem, id. Off. 1, 28, 98; id. Ac. 2, 17: hominum, Liv. 23, 23.
    In plur.: non adprobationes solum movere, Cic. Or. 71, 236.
    Hence, approbatio testium, approbation, i. e. reception, Auct. ad Her. 2, 6.
  2. II. Proof, confirmation (only in Cic.): haec propositio indiget approbationis, Cic. Inv. 1, 36 and 37: assumptionis, proof of the minor proposition, id. ib. 1, 34.