pl. n. level caps; adj. level-capped; v. level capping, capping levels
in tabletop and computer role-playing games with character levels, the highest level attainable; from level (“position on a scale”) + cap (“lid, cover”). Ex: I know you don’t have a 90th level Pandaren Shaman, because the level cap in Cataclysm is 85. Poseur.
Addendum: Generally, level caps exist so there will be some consequences as to what skills and abilities you choose when at lower levels; otherwise, you could just collect everything in the game. Also, level caps exist to keep player characters from becoming too godlike.