In*sol"u*ble (?), a. [L. insolubilis indissoluble, that can not be loosed: cf. F. insoluble. See In- not, and Soluble, and cf. Insolvable.]

1. Not soluble; in capable or difficult of being dissolved, as by a liquid; as, chalk is insoluble in water.

2. Not to be solved or explained; insolvable; as, an insoluble doubt, question, or difficulty.

3. Strong. "An insoluble wall." [Obs.] Holland

• that cannot be dissolved
  
• that cannot be solved; insolvable
  
• that cannot be explained; mysterious or inexplicable