Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
fĕrōcŭlus, a, um, adj. dim. [ferox], somewhat spirited or fierce (very rare): eja, quam ferocula’st! Turp. ap. Non. 75, 30: quid tu, miles tiro, tam feroculus es, Auct. B. Afr. 16, 1.