Challenge  —n. 1 summons to take part in a contest etc. Or to prove or justify something. 2 demanding or difficult task. 3 objection made to a jury member. 4 call to respond. —v. (-ging) 1 issue a challenge to. 2 dispute, deny. 3 (as challenging adj.) Stimulatingly difficult. 4 object to (a jury member, evidence, etc.).  challenger n. [latin calumnia calumny]