Definition of "grownup" []

• An adult. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "John Edwards today said that after watching his rivals slug it out last night, he's proud to represent what he's calling the grownup wing of the Democratic Party."
• "He has to work with a grownup, which is Nancy Pelosi."
• "We're missing the so-called grownup, the adult in the Democratic Party, so expect these two to go at each other tonight -- Kitty."