Answer: opposable

AnswerCrossword Clue
OPPOSABLEThumblike
OPPOSABLEOpen to contravention
OPPOSABLESubject to being challenged
OPPOSABLELike our thumbs
opposablecapable of being placed opposite to something else
opposablecapable of being resisted, fought, or opposed
opposablethat can be opposed