1. 1. Marked by no peculiar quality; not distinguished; ordinary: an undistinguished appearance.
   2. Lacking particularly good qualities; mediocre: an undistinguished performance.
2. Not separated from others into categories.
3. Unnoticed; unperceived: an undistinguished face in the crowd.

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.