late 14c. dissolven, "to break up, disunite, separate into parts" (transitive, of material substances), also "to liquefy by the disintegrating action of a fluid," also intransitive, "become fluid, be converted from a solid to a liquid state," from Latin dissolvere "to loosen up, break apart," from dis- "apart" (see dis-) + solvere "to loosen, untie," from PIE *se-lu-, from reflexive pronoun *s(w)e- (see idiom) + root *leu- "to loosen, divide, cut apart."
General sense of "to melt, liquefy by means of heat or moisture" is from late 14c. Meaning "to disband" (a parliament or an assembly) is attested from early 15c. Related: Dissolved; dissolving.