Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
immĕdĭtātus (inm-), a, um, adj. [inmeditatus], unstudied, unpremeditated, artless, natural (post-class.): sonores animalium, App. Flor. p. 357, 41: incessus, id. Met. 2, p. 115, 25.
Adv.: immĕdĭtātē, without premeditation, Gell. praef. § 10.