Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
lăcertōsus, a, um, adj. [1. lacertus], muscular, brawny, powerful (cf. nervosus): equus, Varr. R. R. 2, 7, 13: centuriones, * Cic. Phil. 8, 9, 26: viri, Col. 1, 9, 4: colonus, Ov. M. 11, 33.