Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
offātim, adv. [offa], in bits, by bits or little pieces (ante- and post-class.): jam hercle ego te hic hac (machaerā) offatim conficiam, Plaut. Truc. 2, 7, 52; Isid. Orig. 20, 2.