Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
incunctābĭlis, e, adj. [2. in-cunctor], that admits of no delay: illud quoque incunctabile est, ut, etc., Dig. 22, 5, 21.
Hence, adv.: incunctābĭlĭter, unhesitatingly, without delay, Alcim. Sent. ad Phil. 4.