Lewis & Short

ex-pando, pandi, pansum or passum (the former, Plin. 2, 103, 106, § 228; 9, 33, 52, § 103; 31, 6, 37, § 70; the latter, Caecil. ap. Gell. 15, 15, 2; but in Tac. H. 5, 13, very dub., the more prob. reading being exapertae, v. Orell. ad h. l.), 3, v. a., to spread out, spread apart, to expand (mostly post-Aug.; not in Cic.).

  1. I. Lit.: haec nuntiasse et flammeum expassum domi, Caecil. ap. Gell. 15, 15, 2: vestes supra fontem frigidum, Plin. 2, 103, 106, § 228: vellera circa navim, id. 31, 6, 37, § 70: alas (grues), id. 10, 38, 54, § 111: ficus in sole, Col. 12, 15, 3: herbas sub umbra, id. 12, 13, 2 et saep.
    Mid.: vagus ille, cum expanditur, amnis (Nilus), Plin. Pan. 30, 4.
  2. * II. Trop.: rerum naturam dictis, to lay open, unfold, explain, Lucr. 1, 126.