Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
frustātim, adv. [frustum], piecemeal, in pieces (very rare): objectare leonibus prandium, Pompon. ap. Non. 113, 7: coquitur in olla, aut frustatim in patinis, Plin. 20, 9, 39, § 99; Prud. Psych. 720.