AGEIST

A person who behaves in an ageist manner.

"He didn’t like to think of himself as an ageist, but he had to admit that he hadn’t considered the needs of some of the more elderly participants."

Unfairly discriminatory against someone based on their age.

"Even though she had succeeded in the phone interview, when the ageist employer learned that the candidate was only 18 years old, she became hesitant."