Online Etymology Dictionary

solitaire (n.): c. 1500, "widow;" 1716, "solitary person, recluse," from French solitaire, from Latin adjective solitarius "alone, lonely, isolated" (see solitary). Sense of "a precious stone set by itself" is from 1727. Meaning "card game played by one person" is first attested 1746.
solitary (adj.): mid-14c., "alone, living alone," from Old French solitaire, from Latin solitarius "alone, lonely, isolated," from solitas "loneliness, solitude," from solus "alone" (see sole (adj.)). Meaning "single, sole, only" is from 1742. Related: Solitarily; solitariness. As a noun from late 14c.; from 1854 as short for solitary confinement (that phrase recorded from 1690s).
solitude (n.): mid-14c., from Old French solitude "loneliness" (14c.) and directly from Latin solitudinem (nominative solitudo) "loneliness, a being alone; lonely place, desert, wilderness," from solus "alone" (see sole (adj.)). "Not in common use in English until the 17th c." [OED]
A man can be himself only so long as he is alone; ... if he does not love solitude, he will not love freedom; for it is only when he is alone that he is really free. [Schopenhauer, "The World as Will and Idea," 1818]
Solitudinarian "recluse, unsocial person" is recorded from 1690s.
solmization (n.): "act of using certain syllables to name tones of a music scale," 1730, from French solmisation, from solmiser, from sol + mi, two of the syllables so used (see gamut).
solo (n.): 1690s, "piece of music for one voice or instrument," from Italian solo, literally "alone," from Latin solus "alone" (see sole (adj.)). As an adjective in English from 1712, originally in the non-musical sense of "alone, unassisted;" in reference to aircraft flying from 1909. The verb is first attested 1858 in the musical sense, 1886 in a non-musical sense. Related: Soloed; soloing.
soloist (n.): 1839, from solo (n.) + -ist.
Solomon: masc. proper name, Biblical name of David's son, king of Judah and Israel and wisest of all men, from Greek Solomon, from Hebrew Sh'lomoh, from shelomo "peaceful," from shalom "peace." The Arabic form is Suleiman. The common medieval form was Salomon (Vulgate, Tyndale, Douai); Solomon was used in Geneva Bible and KJV. Used allusively for "a wise ruler" since 1550s. Related: Solomonic; Solomonian. The Solomon Islands were so named 1568 by Spanish explorers in hopeful expectation of having found the source of the gold brought to King Solomon in I Kings ix:29.
solon (n.): "legislator," 1620s, from Greek Solon, name of early lawgiver of Athens, one of the seven sages. Often, especially in U.S., applied (with perhaps a whiff of sarcasm) by journalists to Congressmen, township supervisors, etc. It also is a useful short headline word.
solstice (n.): mid-13c., from Old French solstice (13c.), from Latin solstitium "point at which the sun seems to stand still," especially the summer solstice, from sol "sun" (see sol) + past participle stem of sistere "to come to a stop, make stand still" (see assist (v.)). In early use, Englished as sunstead (late Old English sunstede).
solstitial (adj.): 1550s, from Latin solstitialis, from solstitium (see solstice).
solubility (n.): 1670s, from soluble + -ity.
soluble (adj.): late 14c., "capable of being dissolved," from Old French soluble "expungable, eradicable" (13c.), from Late Latin solubilis "that may be loosened or dissolved," from stem of Latin solvere "loosen, dissolve" (see solve). Meaning "capable of being solved" is attested from 1705. Substances are soluble, not solvable; problems can be either.
solum (n.): Latin, "ground, soil," of unknown origin.
solus (adj.): Latin, "alone" (see sole (adj.)), used in stage directions by 1590s. Masculine; the fem. is sola, but in stage directions solus typically serves for both. Also in phrases solus cum sola "alone with an unchaperoned woman" and solus cum solo "all on one's own," both literally meaning "alone with alone."
solute (adj.): 1890, "dissolved," from Latin solutus, past participle of solvere (see solve). In botany, "free, not adhering" (1760).
solution (n.): late 14c., "a solving or being solved," from Old French solucion "division, dissolving; explanation; payment" or directly from Latin solutionem (nominative solutio) "a loosening or unfastening," noun of action from past participle stem of solvere "to loosen, untie, solve, dissolve" (see solve). Meaning "liquid containing a dissolved substance" is first recorded 1590s.
solvable (adj.): 1640s, from solve + -able.
solvation (n.): 1909, noun of action from solvate, a verb used in chemistry, from solvent + -ate (2).
solve (v.): late 14c., "to disperse, dissipate, loosen," from Latin solvere "to loosen, dissolve; untie, release, detach; depart; unlock; scatter; dismiss; accomplish, fulfill; explain; remove," from PIE *se-lu-, from reflexive pronoun *s(w)e- (see idiom) + root *leu- "to loosen, divide, cut apart" (see lose). The meaning "explain, answer" is attested from 1530s; for sense evolution, see solution. Mathematical use is attested from 1737. Related: Solved; solving.
solvency (n.): 1727, from solvent + -cy.
solvent (adj.): 1650s, "able to pay all one owes," from French solvent, from Latin solventem (nominative solvens), present participle of solvere "loosen, dissolve" (see solve).
solvent (n.): "substance able to dissolve other substances," 1670s, from Latin solventem (see solvent (n.)).
solvitur ambulando: an appeal to practical experience for a solution or proof, Latin, literally "(the problem) is solved by walking," originally in reference to the proof by Diogenes the Cynic of the possibility of motion.
soma (n.): name of an intoxicant used in ancient Vedic ritual, prepared from the juice of some East Indian plant, 1785, from Sanskrit soma, from PIE *seu- "juice," from root *seue- (2) "to take liquid" (see sup (v.2)). In "Brave New World" (1932), the name of a state-dispensed narcotic producing euphoria and hallucination.
Somalia: country named for the indigenous Somali people, whose name (attested in English by 1814) is of unknown origin.
somatic (adj.): "pertaining to the body" (as distinct from the soul, spirit, or mind), 1775, from French somatique and directly from Greek somatikos "of the body," from soma (genitive somatos) "the body" (see somato-).
somatization (n.): 1909 in biology (Rignano); 1920 in psychology; from somato- "body" + -ization.
somato-: before vowels somat-, word-forming element meaning "the body of an organism," from comb. form of Greek soma (genitive somatos) "the body, a human body dead or living, body as opposed to spirit; material substance; mass; a person, human being; the whole body or mass of anything," of uncertain origin.
somatosensory (adj.): 1952, from somato- "body" + sensory.
somber (adj.): 1760 "gloomy, shadowy" (earlier sombrous, c. 1730), from French sombre "dark, gloomy," from Old French sombre (14c.), from an adjective from Late Latin subumbrare "to shadow," from sub "under" (see sub-) + umbra "shade, shadow," perhaps from a suffixed form of PIE *andho- "blind, dark" (see umbrage). Related: Somberly; somberness.
sombre (adj.): chiefly British English spelling of somber (q.v.); for spelling, see -re.
sombrero (n.): 1770, from Spanish sombrero "broad-brimmed hat," originally "umbrella, parasol" (a sense found in English 1590s), from sombra "shade," from Late Latin subumbrare (see somber).
some (adj.): Old English sum "some, a, a certain one, something, a certain quantity; a certain number;" with numerals "out of" (as in sum feowra "one of four"); from Proto-Germanic *suma- (source also of Old Saxon, Old Frisian, Old High German sum, Old Norse sumr, Gothic sums), from PIE *smm-o-, suffixed form of root *sem- (1) "one," also "as one" (adv.), "together with" (see same). For substitution of -o- for -u-, see come.
The word has had greater currency in English than in the other Teutonic languages, in some of which it is now restricted to dialect use, or represented only by derivatives or compounds .... [OED]
As a pronoun from c. 1100; as an adverb from late 13c. Meaning "remarkable" is attested from 1808, American English colloquial. A possessive form is attested from 1560s, but always was rare. Many combination forms (somewhat, sometime, somewhere) were in Middle English but often written as two words till 17-19c. Somewhen is rare and since 19c. used almost exclusively in combination with the more common compounds; somewho "someone" is attested from late 14c. but did not endure. Scott (1816) has somegate "somewhere, in some way, somehow," and somekins "some kind of a" is recorded from c. 1200. Get some "have sexual intercourse" is attested 1899 in a quote attributed to Abe Lincoln from c. 1840.
somebody (n.): c. 1300, "indeterminate person," from some + body. Meaning "important person, person of consequence" is from 1560s. Somebody else is from 1640s; meaning "romantic rival" is from 1911.
someday (adv.): "at some indefinite date in the future," 1768, from some + day.
MISS SOMEDAY.
Poor Charley wooed, but wooed in vain,
From Monday until Sunday;
Still Cupid whisper'd to the swain
"You'll conquer Betsey Someday."

["The Port Folio," June 1816]
somedeal (adv.): "to some degree, somewhat," obsolete, but very common in Old English as sume dæle "some portion, somewhat," from some + deal (n.1).
somehow (adv.): 1660s, "in some way not yet known," from some + how. First attested in phrase somehow or other.
someone (pron.): c. 1300, sum on; from some + one. Someone else "romantic rival" is from 1914.
someplace (adv.): 1853, from some + place (n.).
somersault (n.): 1520s, from Middle French sombresault, from Old Provençal sobresaut, from sobre "over" (from Latin supra "over;" see supra-) + saut "a jump," from Latin saltus, from the root of salire "to leap" (see salient (adj.)). Sometimes further corrupted to somerset, etc.
somersault (v.): 1845, from somersault (n.). Related: Somersaulted; somersaulting.
Somerset: 9c., Sumor sæton, from Old English sumorsæta, short for *sumorton sæte "the people who live at (or depend upon) Somerton," a settlement attested from 8c. (Sumertone), literally "summer settlement." In 12c. it begins to be clearly meant as a place-name (Sumersetescir) not a collective name for a set of people.
something (pron.): Old English sum þinge; see some + thing. Hyphenated from c. 1300; one word from 17c. Formerly common as an adverb (as in something like). Meaning "some liquor, food, etc." is from 1570s. Meaning "a thing worthy of consideration" is from 1580s; emphatic form something else is from 1909. Phrase something for nothing is from 1816. To make something of is from 1778.
sometime (adv.): late 13c., "at one time or another" (adv.); as an adjective, late 15c. Meaning "at some future time" is late 14c. From some + time (n.).
sometimes (adv.): "now and then," 1520s, from sometime + adverbial genitive -s.
somewhat (adv.): c. 1200, "in a certain amount, to a certain degree," from some + what. Replaced Old English sumdæl, sume dæle "somewhat, some portion," literally "some deal."
somewhere (adv.): c. 1200, from some + where.
somewhile (adv.): mid-12c., from some + while (n.).
somewhither (adv.): late 14c., from some + whither.
sommelier (n.): wine waiter, 1889, from French sommelier "a butler," originally an officer who had charge of provisions (13c.), from somme "pack" (12c.), from Vulgar Latin *salma, corruption of sagma "a pack-saddle," later the pack on the saddle (Isidore of Seville). Also borrowed in 16c.