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**Latin numbers**
	80
← 7	VIII 8	9 →
Cardinal: octō Ordinal: octāvus Adverbial: octiēs, octiēns Proportional: octuplus, octōplus Multiplier: octuplex, octiplex Distributive: octōnus Fractional: octāns, sēscūncia, sēsquūnx, sēscūnx

From Proto-Italic *oktāwos, from Proto-Indo-European *oḱtṓwos, from *oḱtṓw, whence octō (“eight”).

octāvus (feminine octāva, neuter octāvum); first/second-declension numeral

First/second-declension adjective.

	masculine	feminine	neuter	masculine	feminine	neuter
	singular			plural
nominative	octāvus	octāva	octāvum	octāvī	octāvae	octāva
genitive	octāvī	octāvae	octāvī	octāvōrum	octāvārum	octāvōrum
dative	octāvō	octāvae	octāvō	octāvīs
accusative	octāvum	octāvam	octāvum	octāvōs	octāvās	octāva
ablative	octāvō	octāvā	octāvō	octāvīs
vocative	octāve	octāva	octāvum	octāvī	octāvae	octāva

“octavus”, in Charlton T. Lewis and Charles Short (1879), A Latin Dictionary, Oxford: Clarendon Press
“octavus”, in Charlton T. Lewis (1891), An Elementary Latin Dictionary, New York: Harper & Brothers
"octavus", in Charles du Fresne du Cange, Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
“octavus”, in Gaffiot, Félix (1934), Dictionnaire illustré latin-français, Hachette.

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