challenge

a challenge to a duel.

a challenge to a theory.

challenge sb. to a duel

a challenge to the government's authority.

It is possible to challenge the report's assumptions.

an Asian challenge to occidental dominance.

the challenge was to avoid institutional sclerosis.

a formidable challenge; a formidable opponent.

a challenge to the legality of the banning order.

a challenge to the ethos of the 1960s.

an ethically challenged politician.

Brace yourself for a new challenge!

challenged me to a game of chess.

events that challenge our attention.

a problem that challenges the imagination.

The job doesn't really challenge him.

He had met the challenge and triumphed.

I challenged the truth of their story.