1. The earliest period of childhood, especially before the ability to walk has been acquired.
2. The state of being an infant.
3. An early stage of existence: Space exploration is still in its infancy.
4. Law. The state or period of being a minor.

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.