Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
ūsurpātīvē, adv., v. usurpativus fin.
ūsurpātīvus, a, um, adj. [usurpo, II. B. 2.], wrongly used, unusual, improper, usurpative (late Lat.): species verborum, Diom. p. 389 P.; Macr. Diff. Verb. p. 2764 ib.
Adv.: ūsurpātīvē, in an unusual manner, improperly, wrongly: usurpative ait hordea, Serv. ad Verg. G. 1, 210; id. ad Verg. A. 7, 289.