1. Of, relating to, or suitable for a child or childhood: a high, childish voice; childish nightmares.
2. 1. Marked by or indicating a lack of maturity; puerile: tired of your childish pranks.
   2. Not complicated; simple.
   3. Affected mentally by old age; senile.

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.