aestas

From Proto-Italic *aissāts, with the suffix -tāt-s restored via analogy. The root is from Proto-Indo-European *h₂eydʰ- (“burn; fire”), and has cognates in Latin aestus, perhaps aedis, Ancient Greek αἴθω (aíthō)), Old English ād (“pyre”). The noun suffix is from Proto-Indo-European *-teh₂ts.

De Vaan criticizes a prevalent simple etymology from *h₂e-h₂idʰ-teh₂t-s (with an i-reduplicated root) as unfounded, also observing -dʰt- becomes -ss- in Latin rather than -st-, preferring instead *h₂eydʰ-teh₂ts > Proto-Italic *aissāt-s, which then had the suffix -t- consonant restored.

• (Classical) IPA^(key): /ˈae̯s.taːs/, [ˈäe̯s̠t̪äːs̠]
• (modern Italianate Ecclesiastical) IPA^(key): /ˈes.tas/, [ˈɛst̪äs]
• Rhymes: -aːs

aestās f (genitive aestātis); third declension

1. summer

Third-declension noun.

• aestīvus

• aestus

• De Vaan, Michiel (2008) “aestās”, in Etymological Dictionary of Latin and the other Italic Languages (Leiden Indo-European Etymological Dictionary Series; 7), Leiden, Boston: Brill, →ISBN, page 28
• “aestas”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
• “aestas”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
• aestas in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.
• Carl Meißner, Henry William Auden (1894) Latin Phrase-Book‎, London: Macmillan and Co.
  • in the height of summer, depth of winter: summa aestate, hieme
    
• Walther von Wartburg (1928–2002) “aestas”, in Französisches Etymologisches Wörterbuch (in German), volumes 24: Refonte A–Aorte, page 229