Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
ŏperto, āre, v. freq. a. [operio], to cover (ante-class.): opertat saepe opertit, Fest. p. 191 Müll.; Enn. ap. Non. 223, 30 (Ann. v. 500 Vahl.): continuo operta denuo, Plaut. Trin. 3, 3, 75 Fleck. (Ritschl, operi).