late 14c., solucioun, "explanation, answer; interpretation of a dream; the dissolving of a substance in a liquid, transformation of matter to a liquid state," from Old French solucion "division, dissolving; explanation; payment" and directly from Latin solutionem (nominative solutio) "a loosening or unfastening," noun of action from past-participle stem of solvere "to loosen, untie, dissolve," from PIE *se-lu-, from reflexive pronoun *s(w)e- (see idiom) + root *leu- "to loosen, divide, cut apart."

The meaning "liquid containing a dissolved substance" is recorded by 1590s.

"substance enclosed under pressure and able to be released as a fine spray," 1919, from aero- "air" + first syllable in solution, in the chemical sense. A term in physics; modern commercial application is from 1940s.

1947, translation of German Endlösung, name given to Nazi Jewish policy from 1941.

Proto-Indo-European root meaning "to loosen, divide, cut apart."

It forms all or part of: absolute; absolution; absolve; analysis; analytic; catalysis; catalyst; catalytic; dialysis; dissolve; electrolysis; electrolyte; forlorn; Hippolytus; hydrolysis; -less; loess; loose; lorn; lose; loss; Lysander; lysergic; lysis; -lysis; lyso-; lysol; lytic; -lytic; palsy; paralysis; pyrolusite; resolute; resolution; resolve; soluble; solute; solution; solve; solvent.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit lunati "cuts, cuts off," lavitram "sickle;" Greek lyein "to loosen, untie, slacken," lysus "a loosening;" Latin luere "to loose, release, atone for, expiate;" Old Norse lauss "loose, free, unencumbered; vacant; dissolute;" Old English losian "be lost, perish."

"crucially important," 1913, from key (n.1). Perhaps from or reinforced by key move, in chess, "first move in a solution to a set problem" (1827), which to an experienced player opens the way to see how the solution will develop.

"the operation or practice of fixing colors in solution in textiles, hides, hair, etc.," late 14c., verbal noun from dye (v.).

"something that is added" to a chemical solution or food product, 1945, from additive (adj.).

in chemistry, "a substance dissolved in a solution," by 1893, from Latin solutus, past participle of solvere (see solve (v.)).

in chemistry, "the establishment of a standard strength or degree of concentration of a solution," 1864, noun of action from titrate (v.).

also antifreeze, "liquid added to water to lower its freezing point," typically used in the radiator of an automobile engine, 1935, shortening of anti-freeze solution (1913); see anti- + freeze (v.).