Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
trĭbūtim, adv. [tribus], through each tribe, tribe by tribe, by tribes: tributim et centuriatim descriptis ordinibus, Cic. Fl. 7, 15: legem centuriatis comitiis tulere, ut quod tributim plebes jussisset, populum teneret, i. e. in the comitia tributa, Liv. 3, 55, 3; cf. id. 7, 16, 7: nummis tributim divisis, Cic. Att. 4, 17, 1: spectacula tributim data, id. Mur. 34, 72; cf. id. ib. 32, 67: arripuit populum tributim, Hor. S. 2, 1, 69.