Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
pūmĭcōsus, a, um, adj. [pumex], like pumice-stone, i. e. porous: terra, Plin. 17, 5, 3, § 34; Vitr. 2, 3: lapis, Plin. 36, 19, 34, § 141.
Comp.: halcyoneum, Plin. 32, 8, 27, § 86.