(1) Susceptible of being dissolved in some solvent, as in sugar being soluble in water (solvent).
(2) That can be solved or explained, as in a soluble problem.
Word origin: Middle English, from Old French, from Late Latin solūbilis, from Latin solvere, to loosen.
Related forms: insoluble (adjective).
Related phrases: fat-soluble vitamins, fat soluble, soluble antigen, soluble starch.
See also: solubility.