senium

• (Classical Latin) IPA^(key): [ˈsɛ.ni.ũː]
• (modern Italianate Ecclesiastical) IPA^(key): [ˈsɛː.ni.um]

From seneō (“I am weak, feeble”) +‎ -ium.

senium n (genitive seniī or senī); second declension

1. feebleness of age, decline, debility
2. (rare) old man
3. peevishness, chagrin, mortification, grief

Second-declension noun (neuter).

¹Found in older Latin (until the Augustan Age).

• senex

senium

1. genitive masculine/feminine/neuter plural of senex
   • 1605, Giovanni Battista Bernardo, Seminarium totius philosophiae Aristotelicae, Platonicae et stoicae, Book 3, page 23:

     Dentes equorum senium sunt albi

     The teeth of aged horses are white.

   • 1855, Enchiridion medicinae pastoralis..., page 94:

     Noxia est caro animalium senium, macrorum, tempore aestivo praesertim diutius conservata.

     (please add an English translation of this quotation)

   • 1888, “Apuana Funerum”, in Causae proponendae in congregatione diei 17 decembris 1881, per summaria precum, page 5:

     Cui accedunt testimonia nonnullorum aliorum virorum senium et spectabilium, nempe [...]

     (please add an English translation of this quotation)

• “senium”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
• “senium”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
• "senium", in Charles du Fresne du Cange’s Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
• senium in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.
• Carl Meißner, Henry William Auden (1894) Latin Phrase-Book‎^[1], London: Macmillan and Co.
  • (ambiguous) to be worn out by old age: senectute, senio confectum esse