Lewis & Short

sŭperlātĭo, ōnis, f. [superfero].

  1. I. In rhet., an exaggerating, hyperbole: veritatis superlatio atque trajectio, Cic. de Or. 3, 53, 203; cf. Auct. Her. 4, 33, 44; Quint. 9, 2, 3; 9, 1, 29; 12, 10, 62: malignitatis, the highest degree, App. Dogm. Plat. 2, p. 20, 40.
  2. II. In gram., the superlative: (soloecismus) per comparationes et superlationes, Quint. 1, 5, 45; Charis. p. 88 sq. P.