Source : Webster's Revised Unabridged Dictionary (1913)

Irresolvable \Ir`re*solv"a*ble\, a. [Pref. ir- not + resolvable.
   Cf. {Irresoluble}.]
   Incapable of being resolved; not separable into component
   parts.

   {Irresolvable nebul[ae]} (Astron.), nebul[ae] of a cloudlike
      appearance, which have not yet been resolved by the
      telescope into stars.