Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
tentāmen, ĭnis, n. [tento], a trial, essay, attempt (poet.; perh. only in the two foll. passages): prima vocis tentamina sumpsit, Ov. M. 3, 341: tentamina Repellere, id. ib. 7, 734.