senectitude|sɪˈnɛktɪtjuːd| [ad.med.L. senectitūd-o (c 800 in Du Cange), irreg.f.senectūs: see senectute and -tude.] Old age. 1796Mod. Gulliver 49 Persons, of all ages, from twenty to extreme senectitude.1898B. Gregory Side Lights 482 Replete with the mild wisdom of senectitude.