Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
mirmillōnĭcus (myrm-), a, um, adj. [mirmillo], of or belonging to a mirmillo: genus armaturae, of the mirmillones, Paul. ex Fest. s. v. retiario, p. 284 and 285 Müll.; v. mirmillo: myrmillonica scuta dicebant, cum quibus de muro pugnabant, Paul. ex Fest. p. 144, 12.