Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
grandaevus, a, um, adj. [grandisaevum], in years, old, aged (poet. and in post-Aug. prose): Nereus, Verg. G. 4, 392: Alethes, id. A. 1, 121: Emathion, Ov. M. 5, 99: pater, id. ib. 8, 519: patres, id. ib. 7, 160: senes, Tac. H. 3, 33: manus, i. e. the Senate, Sil. 16, 653: alios (deos) esse grandaevos semperque canos, alios juvenes atque pueros, Plin. 2, 7, 5, § 17: apes, Verg. G. 4, 178: consilia, of an aged man, Val. Fl. 7, 348.