(1):

(a.) Susceptible of being solved; as, a soluble algebraic problem; susceptible of being disentangled, unraveled, or explained; as, the mystery is perhaps soluble.

(2):

(a.) Relaxed; open or readily opened.

(3):

(a.) Susceptible of being dissolved in a fluid; capable of solution; as, some substances are soluble in alcohol which are not soluble in water.