ineffectible

From in- +‎ effectible.

ineffectible (comparative more ineffectible, superlative most ineffectible)

1. (archaic) ineffectual; impracticable
   • a. 1656, Joseph Hall, The Soul's Farewell to Earth:

     There he , in an ineffectible manner , communicates himself to blessed spirits , both angels and men ; and that very vision is no less to them than beatifical.

• “ineffectible”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.