undecentum

• Symbol: XCIX

Literally "one from one hundred"; ūnus (“one”) + dē (“from”) + centum (“hundred”)

• (Classical) IPA^(key): /uːn.deːˈken.tum/, [uːn.deːˈkɛn.tũ]

ūndēcentum (indeclinable)

1. (cardinal) ninety-nine; 99
   • 77-78 — Pliny the Elder, Naturalis Historia, Book VII, section 214

     nec congruēbant ad hōrās eius līneae, pāruērunt tamen eī annīs ūndēcentum, ...

     Although the threads did not come together for those hours, they were evident those ninety-nine years, ...

Although ūndēcentum is the usual expression for 99, it is also possible to say nōnāgintā novem (“ninety-nine”) or novem et nōnāgintā (“nine and ninety”).

• centum

• Appendix:Latin cardinal numbers

• undecentum in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
• undecentum in Gaffiot, Félix (1934) Dictionnaire Illustré Latin-Français, Hachette