definition of
challenge

[1] #1 challenge v. [dispute, gainsay] take exception to; "She challenged his claims". wn

[2] #2 challenge v. issue a challenge to; "Fischer challenged Spassky to a match". wn

[3] #3 challenge n. a demanding or stimulating situation; "they reacted irrationally to the challenge of Russian power". wn

[4] #4 challenge n. a call to engage in a contest or fight. wn

[5] #5 challenge n. questioning a statement and demanding an explanation; "his challenge of the assumption that Japan is still our enemy". wn