Agist

[Sarah]

To take to graze or pasture, at a certain sum; -- usedoriginally of the feeding of cattle in the king's forests, andcollecting the money for the same. Blackstone.

[Sarah]

Ageist = discrimination on the basis of age.
Agist = graze cattle on pasture for payment.

[Sarah]

To discriminate against somebody's age. Telling some one he/she is too young to do something. It's like being sexist but against age.

[Sarah]

A person who discriminates against people that are not their age.

[Sarah]

Someone who uses [agism], usually by an adult who obviously cannot remember his or her childhood becuase if they did they'd think that kids deserve [rights].

[Dave Paprocki]

Judging someone by his or her age.

[Justin Bieber]

[Age] [racist].
[Racism] towards [age]