"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.
initialism from shit out of luck (though sometimes euphemised), 1917, World War I military slang. "Applicable to everything from death to being late for mess" [R. Lord, "Captain Boyd's Battery A.E.F."]
sol (sôl, sōl)
n.
A colloidal dispersion of a solid in a liquid.
sol. abbr.
solution
Shit out of luck; ruined; kaput: If the press gets ahold of this, we're SOL
[WWI armed forces; fr shit out of luck]
1.
2. Second-Order lambda-calculus.
3. Semantic Operating Language. Language for manipulating semantic networks for building cognitive models, particularly for natural language understanding. "Explorations in Cognition", D.A. Norman et al, W.H. Freeman 1974.
4. Shit Outta Luck.
in physical chemistry, a colloid (aggregate of very fine particles dispersed in a continuous medium) in which the particles are solid and the dispersion medium is fluid. If the dispersion medium is water, the colloid may be called a hydrosol; and if air, an aerosol. Lyophobic (Greek: "liquid-hating") sols are characterized by particles that are not strongly attracted to molecules of the dispersion medium and that are relatively easily coagulated and precipitated. Lyophilic ("liquid-loving") sols are more stable and more closely resemble true solutions. Many sols are intermediate between lyophobic and lyophilic types. Compare gel.