Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
ăsĭnīnus, a, um, adj. [asinus], of or produced by an ass: stercus, Varr. R. R. 1, 38, 2: pullus, ass’s foal, a young ass, id. ib. 2, 8: pilus, Plin. 8, 21, 30, § 72, where Jan reads asini: pruna asinina cognominata a vilitate, id. 15, 13, 12, § 41.