Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
mīlĭārensis (millĭārensis), e, adj. [mille], that contains a thousand (post-class.): porticus, either containing a thousand columns, or containing a thousand paces, Vop. Aur. 49: COHORS, Inscr. Marin. Frat. Arv. p. 630.