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.

Source: Webster's Revised Unabridged Dictionary (1913)