Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
per-grandis, e, adj., very large, very great (rare but class.): gemma, Cic. Verr. 2, 4, 27, § 62: vectigal, id. Agr. 1, 4, 9: lucrum, Plaut. Pers. 4, 3, 23: pergrandis natu, very old, very aged, Liv. 29, 29, 6: lapis, Vulg. Josue, 24, 26.