Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
lībrālis, e, adj. [libra], of or containing a pound, of a pound weight: pondus, Plin. 19, 2, 11, § 34: offae, Col. 6, 2, 7: veluti asses librales erant, Gai. Inst. 1, 122.