Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
vĭgor, ōris, m. [vigeo], liveliness, activity, force, vigor (mostly poet. and in postAug. prose; not in Cæs. or Cic.): nec tarda senectus Debilitat vires animi mutatque vigorem, Verg. A. 9, 611: igneus est ollis vigor, id. ib. 6, 730: juventas et patrius vigor, Hor. C. 4, 4, 5: animi, Ov. H. 16, 51; Liv. 9, 16: mentis, Quint. 11, 2, 3: quantum in illo (libro), di boni, vigoris est, quantum animi! Sen. Ep. 64, 2: gemmae, strong brilliancy, Plin. 37, 7, 28, § 101; cf. id. 9, 35, 54, § 109.
Plur.: vigores mentium, Gell. 19, 12, 4: animorum, Vitr. 6, 1 fin.; Sil. 15, 355.