challenge noun
B1 [C or U] (the situation of being faced with) something that needs great mental or physical effort in order to be done successfully and therefore tests a person's ability:
Finding a solution to this problem is one of the greatest challenges faced by scientists today.
You know me - I like a challenge.
It's going to be a difficult job but I'm sure she'll rise to the challenge.
challenge verb [T]
› to invite someone to compete or take part, especially in a game or argument:
Tina has challenged me to a game of poker