octodecim

• Symbol: XVIII

From octō (“eight”) + decem (“ten”).

• (Classical Latin) IPA^(key):
• (modern Italianate Ecclesiastical) IPA^(key):

octōdecim (indeclinable)

1. (rare) eighteen; 18
   • 1543, Petrus Comestor, Historia Scholastica, III Kings, "De porticu"

     Quarum talis erat compositio: Stylus, vel stipes columnae octodecim habebat cubitos altitudinis

     (please add an English translation of this quotation)

   • 1687, Isaac Newton, “Axiomata, sive Leges Motus”, in Philosophiae Naturalis Principia Mathematica:

     Si corpus Alucretur partes novem vel decem vel undecim vel duodecim, adeoque progrediatur post concursum cum partibus quindecim vel sexdecim vel septendecim vel octodecim.

     (please add an English translation of this quotation)

This form is rare, and is found primarily in bookish post-Classical Latin. The usual word for eighteen in Classical Latin is duodēvīgintī, whereas modern Romance languages descend from the form decim et octō.

• duodēvīgintī

• Appendix:Latin cardinal numbers

• “octodecim”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
• “octodecim”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
• octodecim in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.