Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
armentīcĭus (better, -tĭus), a, um, adj. [armentum], of or relating to a herd of cattle (perh. only in Varr.): pecus, Varr. R. R. 2, 5, 16: greges, id. ib. 2, 10, 3 (Schneid. in Veg. 1, 18 reads armentiva).