Reconstruction:Proto-Indo-European/h₂eh₁ter-

From *h₂eh₁- (“to be hot, warm, dry”) +‎ *-tēr (agentive nominal suffix).

The root is found functionally in Palaic 𒄩𒀀 (ḫa-a /⁠ḫā⁠/, “to be hot”)[1] and with another derivative in Proto-Celtic *ā-ti- f (“drying kiln”).[2] More at *h₂eHs-.

*h₂eh₁ter-

1. fire

   Synonyms: *h₁n̥gʷnís, *péh₂wr̥

• *h₂éh₁tēr m or f[3]
• *h₂éh₁tr̥ n[4]

• The original gender of the noun is unreconstructible. It may have been either masculine/feminine *h₂éh₁tēr or neuter *h₂éh₁tr̥, or both may have existed in semantic opposition (compare the near-synonyms *h₁n̥gʷnís m and *péh₂wr̥ n).

• >? Albanian: vatër, votër (see there for further descendants)
• Proto-Armenian:
  • Old Armenian: *այր (*ayr, “fire”), ⇒ այրեմ (ayrem, “to burn”), ⇒ զայրանամ (zayranam, “to become angry”)
• Italic:
  • Latin: āter (“matte black”) (possibly in sense of “blackened by fire”), atrox (“fierce”), Atella (“an ancient Oscan city in Campania”), ātrium (“welcoming room”), Atrius (“a family name”)
  • Umbrian: 𐌀𐌕𐌓𐌖 (atru, “black”)
  • Oscan: 𐌀𐌀𐌃𐌝𐌓𐌉𐌉𐌔 (aadíriis, “familial name akin to Latin 'Atrius'”)
• Indo-Iranian: *HáHtr̥š (“fire”)
  • Iranian: *HáHtr̥š (“fire”) (see there for further descendants)
    • Avestan: 𐬁𐬙𐬀𐬭 (ātar, “fire”)
    • → Old Armenian: ատր- (atr-)

• *h₂eHs- (“to be/become dry, to burn, to glow, hearth, ashes”)
• *h₂eh₃- (“to be hot, to burn”)
• *h₁engʷ- (“to burn, fire”)
• *h₁ews- (“to burn”)