sóh₂wl̥

The PIE sun word *sóh₂wl̥ belongs to the heteroclitic l/n-stem class, with a nominative in *-l and oblique cases showing an n-stem (*sh₂wéns for the genitive). This archaic morphological pattern, shared with the words for water and fire, marks it as part of the oldest stratum of the PIE vocabulary. Latin sōl (genitive sōlis, "sun") preserves the root transparently. Derivatives include solar, solarium, solstice (sōlstitium, "sun-standing," the point at which the sun appears to pause), and parasol ("against the sun"). The word Sunday (Old English Sunnandæg, calqued on Latin diēs Sōlis) indirectly reflects the same root. Greek hḗlios (ἥλιος, "sun") shows a more complex development: *sh₂wél- > *sāwel- > *hāwel- > hḗlios, with compensatory lengthening and the characteristic Greek prothetic aspiration. Derivatives include heliocentric, heliograph, helium (named for the element first detected in the solar spectrum), and the name Helios, the sun god. Sanskrit sū́rya (from *sh₂wél-yo-) shows a different suffixal extension. Sūrya is the name of the Vedic sun deity, and the Sūrya Namaskāra ("sun salutation") is a widely practised yoga sequence. Gothic sauil and Old Norse sól continue the Germanic reflex. English sun descends from a different formation (*sunnōn, a derivative of the same root), while sol survives in learned compounds and in the name of the musical note sol (from the hymn to St. John). Lithuanian sáulė ("sun") and Latvian saule preserve the Balto-Slavic reflex. The Baltic sun mythology, in which the sun is female (Sáulė is a goddess), contrasts with the masculine sun of Greek and Sanskrit traditions but aligns with the grammatically feminine gender of the sun in Baltic — a point of considerable interest for PIE mythological reconstruction. Welsh haul and Old Irish suil ("eye" — with a semantic shift from "sun" to "eye," the organ that receives sunlight) extend the attestation to Celtic.