Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
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.).