Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
ūtĭbĭlis, e, adj. [utor], that can be used, fit, appropriate, useful, serviceable (colloq. and ante-class.): non utibilis hic locus factis tuis, Plaut. Merc. 5, 4, 45: servi eris, id. Most. 4, 1, 2; id. Men. 5, 6, 23: ad rem utibile, id. Mil. 3, 1, 19; cf. id. Trin. 3, 3, 19: quid minus utibile fuit quam hoc ulcus tangere? Ter. Phorm. 4, 4, 10: neque aqua utibilis reperta, Auct. Itin. Alex. 37.