1. A child's apprehension associated with separation from a parent or other caregiver.
2. Anxious behavior exhibited by a domestic animal in the absence of its owner or custodian.

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.