Akademik

challenge
n. & v.
—n.
1 a a summons to take part in a contest or a trial of strength etc., esp. to a duel. b a summons to prove or justify something.
2 a demanding or difficult task (rose to the challenge of the new job).
3 Law an objection made to a jury member.
4 a call to respond, esp. a sentry's call for a password etc.
5 an invitation to a sporting contest, esp. one issued to a reigning champion.
6 Med. a test of immunity after immunization treatment.
—v.tr.
1 (often foll. by to + infin.) a invite to take part in a contest, game, debate, duel, etc. b invite to prove or justify something.
2 dispute, deny (I challenge that remark).
3 a stretch, stimulate (challenges him to produce his best). b (as challenging adj.) demanding; stimulatingly difficult.
4 (of a sentry) call to respond.
5 claim (attention, etc.).
6 Law object to (a jury member, evidence, etc.).
7 Med. test by a challenge.
Derivatives:
challengeable adj. challenger n.
Etymology: ME f. OF c(h)alenge, c(h)alenger f. L calumnia calumniari calumny

Useful english dictionary. 2012.