'Soluble' definitions:

Definition of 'soluble'

From: WordNet
adjective
(of a substance) capable of being dissolved in some solvent (usually water) [ant: indissoluble, insoluble]
adjective
Susceptible of solution or of being solved or explained; "the puzzle is soluble" [ant: insoluble]

Definition of 'Soluble'

From: GCIDE
  • Soluble \Sol"u*ble\, a. [L. solubilis, fr. solvere, solutum, to loosen, to dissolve: cf. F. soluble. See Solve, and cf. Solvable.]
  • 1. Susceptible of being dissolved in a fluid; capable of solution; as, some substances are soluble in alcohol which are not soluble in water. [1913 Webster]
  • Sugar is . . . soluble in water and fusible in fire. --Arbuthnot. [1913 Webster]
  • 2. Susceptible of being solved; as, a soluble algebraic problem; susceptible of being disentangled, unraveled, or explained; as, the mystery is perhaps soluble. "More soluble is this knot." --Tennyson. [1913 Webster]
  • 3. Relaxed; open or readily opened. [R.] "The bowels must be kept soluble." --Dunglison. [1913 Webster]
  • Soluble glass. (Chem.) See under Glass. [1913 Webster]