challenge - noun

a demanding or stimulating situation

a call to engage in a contest or fight

questioning a statement and demanding an explanation

a formal objection to the selection of a particular person as a juror

a demand by a sentry for a password or identification

challenge - verb

• take exception to
• issue a challenge to
• ask for identification
• raise a formal objection in a court of law

challenge - thesaurus

dispute   gainsay