tempus aestivum

• (Classical Latin) IPA^(key): [ˈtɛm.pʊs ae̯sˈtiː.wũː]
• (modern Italianate Ecclesiastical) IPA^(key): [ˈt̪ɛm.pus esˈt̪iː.vum]

tempus aestīvum n (genitive temporis aestīvī); third declension

1. (This entry is a descendant hub.) summer-time
   • 1st century CE, Curtius Rufus, Histories of Alexander the Great, book 4:

     Caeli fulgor tempore aestivo ardenti similis internitens ignis praebuit speciem flammasque ex Darei castris splendere velut inlati temere praesidiis credebant.

     With summer-time in full blaze, the sky gleamed in a way that resembled fire, and [Alexander's soldiers] thought that they saw flames shining out from Darius' camp, as if they were under attack from the defenders.

Third-declension noun (neuter, imparisyllabic non-i-stem) with a second-declension adjective.

(All shortened by dropping tempus.)

• Meyer-Lübke, Wilhelm (1911) “aestivus”, in Romanisches etymologisches Wörterbuch (in German), page 16
• Walther von Wartburg (1928–2002) “aestīvus”, in Französisches Etymologisches Wörterbuch, volume 24: Refonte A–Aorte, page 234