Lewis & Short

2. compărātĭo, ōnis, f. [2. comparo].

  1. I. A preparing, providing for, preparation, etc. (rare, but in good prose): novi belli, Cic. Imp. Pomp. 4, 9; cf. pugnae, Auct. B. Afr. 35: veneni, Liv. 42, 17, 6: comparatio disciplinaque dicendi, Cic. Brut. 76, 263: novae amicitiae, Sen. Ep. 9, 6.
  2. II. A procuring, gaining, acquiring: testium, Cic. Mur. 21, 44: voluptatis, id. Fin. 2, 28, 92: criminis, i. e. of all the materials for an accusation, id. Clu. 67, 191: quibus ego ita credo, ut nihil de meā comparatione deminuam, id. Q. Fr. 1, 2, 5, § 16.
    Hence,
    1. B. In late Lat., a purchasing, purchase, Dig. 5, 1, 52; 41, 3, 41.