autumnus

• auctumnus, autumna

From earlier auctumnus, of unclear ultimate origin:

• From Proto-Indo-European *h₃ewǵ- (“cold”) (compare Old Irish úacht, Lithuanian áušti (“to cool off”), Old Armenian ոյծ (oyc)).
• Borrowed from an Etruscan word, like Etruscan 𐌀𐌕𐌖𐌍𐌄 (atune, “autumn”).^[1][2]
• From Proto-Indo-European *h₂sews- (“dry”), as in "drying up season."^[3]

Possibly influenced by auctus (“enriched, enlarged, ample”).

• (Classical Latin) IPA^(key): /au̯ˈtum.nus/, [äu̯ˈt̪ʊmnʊs̠]
• (modern Italianate Ecclesiastical) IPA^(key): /au̯ˈtum.nus/, [äu̯ˈt̪umnus]

autumnus m (genitive autumnī); second declension

1. autumn, fall

Second-declension noun.

autumnus (feminine autumna, neuter autumnum); first/second-declension adjective

1. (relational) autumn; autumnal

First/second-declension adjective.

Several are learned.

• “autumnus”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
• autumnus 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)