Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
* 1. imprŏpĕro (inpr-), āre, v. n. [in-propero], to hasten into, enter hastily: quo si quis improperet, Varr. ap. Plin. 36, 13, 19, § 91.
2. imprŏpĕro (inpr-), āvi, ātum, 1, v. n. and a. [corrupt. for improbro; from in-probrum], to cast as a reproach upon one, to reproach, taunt, upbraid (post-Aug., and very rare): impropero ὀνειδιζω, Gloss. Philox.: non impropero illi, Petr. 38: improperia improperantium, Vulg. Rom. 15, 3: latrones improperabant ei, id. Matt. 27, 44.