Stubborn

Adj. "stubborn, obstinate, perverse," 1610s (earlier refractorious, 1550s, refractary, c.1600), from Latin refractarius "obstinate, stubborn," from past participle stem of refringere (see refraction). Related: Refractorily; refractoriness.

Adj late 14c., of uncertain origin. Earliest form is stiborn. OED, Liberman doubt any connection with stub (n.). Related: Stubbornly; stubbornness.