indocible

From Latin indocibilis. See in- (“not”) +‎ docible.

indocible (comparative more indocible, superlative most indocible)

1. Incapable of being taught, or not easily instructed; dull in intellect; intractable.
   • 1630, Joseph Hall, Occasional meditations

     Let him alone, till time and ill example have hardened him; till he be settled in a habit of evil, and contracted and clung together with sensual delights; now he becomes utterly indocible.

• indocibleness