ADAMANT

(adj.)

Adamant \ˈa-də-mant\

(adj.)

1. unshakable or insistent especially in maintaining a position or opinion ; unyielding.
2. Unwavering, unshakeable, inflexible; esp. (chiefly predicative) refusing to be persuaded or to change one’s mind; absolutely convinced that something is the case.

: Johnny’s adamant mule had no interest in yielding to her owner’s will.

Definition provided by Oxford English Dictionary