How do you make an adjective from challenge?

The most common adjective form of "challenge" is challenging. It describes something that is difficult, demanding, or stimulating.

Here are some examples:

* "This is a challenging task."

* "The students found the exam to be challenging."

* "She enjoys challenging herself with new experiences."

There are other less common adjective forms, like "challenged" which can be used to describe someone with a disability, or "challengeable" which is more formal and means "capable of being challenged." However, challenging is the most widely used and understood adjective derived from "challenge."