A space shuttle, named after HMS Challenger (1858), destroyed on January 28, 1986 with loss of its seven-member crew.

Able to be challenged or disputed.

Full of challenge.

Difficult, hard to do.

present participle of challenge

The act of making a challenge.

plural of challenging

Alternative form of challengeable

(humorous, euphemistic, of a person) Ugly.

(humorous, euphemistic, of a person) Of low intelligence; stupid.