Lewis & Short

explānātĭo, ōnis, f. [explano].

  1. I. An explanation, interpretation (class.): somniis, vaticinationibus, oraculis quod erant multa obscura, explanationes adhibitae sunt interpretum, Cic. Div. 1, 51, 116; cf. aequitatis, id. Rep. 5, 2: unius cujusque propositionis, Auct. Her. 4, 16, 23: illustris sententiae suae (with propositio), Quint. 9, 2, 2: res arduae explanationis, Plin. 10, 68, 87, § 190.
    1. B. In partic., as a fig. of speech, Auct. Her. 4, 12, 17; Cic. de Or. 3, 53, 202; Quint. 9, 1, 27.
  2. II. A distinct articulation, pronunciation: dentes, cum defuere, explanationem omnem adimentes, Plin. 7, 16, 18, § 70: emendata cum suavitate vocum explanatio, Quint. 1, 5, 33: verborum (shortly before: dilucida pronunciatio), id. 11, 3, 33.