"the sun personified," mid-15c. (also in Old English), from Latin sol "the sun, sunlight," from PIE *s(e)wol-, variant of root *saewel- "the sun" (cf. Sanskrit suryah, Avestan hvar "sun, light, heavens;" Greek helios; Lithuanian saule; Old Church Slavonic slunice; Gothic sauil, Old English sol "sun," swegl "sky, heavens, the sun;" Welsh haul, Old Cornish heuul, Breton heol "sun;" Old Irish suil "eye").
The PIE element -*el- in the root originally was a suffix and had an alternative form -*en-, yielding *s(u)wen-, source of English sun (n.). French soleil (10c.) is from Vulgar Latin *soliculus, diminutive of sol; in Vulgar Latin diminutives had the full meaning of their principal words.
"bottom of the foot" ("technically, the planta, corresponding to the palm of the hand," Century Dictionary), early 14c., from Old French sole, from Vulgar Latin *sola, from Latin solea "sandal, bottom of a shoe; a flatfish," from solum "bottom, ground, foundation, lowest point of a thing" (hence "sole of the foot"), of uncertain origin. In English, the meaning "bottom of a shoe or boot" is from late 14c.
common European flatfish, mid-13c., from Old French sole, from Latin solea "a kind of flatfish," originally "sandal" (see sole (n.1)); so called from resemblance of the fish to a flat shoe.
"single, alone, having no husband or wife; one and only, singular, unique," late 14c., from Old French soul "only, alone, just," from Latin solus "alone, only, single, sole; forsaken; extraordinary," of unknown origin, perhaps related to se "oneself," from PIE reflexive root *swo- (see so).
"furnish (a shoe) with a sole," 1560s, from sole (n.1). Related: Soled; soling.
sol (sôl, sōl)
A colloidal dispersion of a solid in a liquid.
The underside of the foot.
Shit out of luck; ruined; kaput: If the press gets ahold of this, we're SOL
[WWI armed forces; fr shit out of luck]