Same word as unapprehensive:

audacious, coming on strong, courageous, dauntless, fearless, fire-eating, gallant, icy, indomitable, intrepid, not discouraged, not put off, resolute, spunky, steadfast, unafraid, unalarmed, unapprehensive, undeterred, undiscouraged, undismayed, unfaltering, unflinching, unshrinking, valiant, valorous