Lewis & Short

castrātĭo, ōnis, f. [castro].

  1. I. An emasculating, castration of animals, Col. 6, 26; 7, 11, 1; Pall. Mai, 7, 3; Dig. 21, 1, 38.
  2. II. A pruning, Plin. 16, 40, 76, § 206.