The meaning of nondescript is "uninteresting, or undistinguished". It can also mean "dull".
The private detective deliberately wore nondescript apparel to avoid notice.
The door was of the nondescript variety common to local residences.
(Here it means dull, or uninteresting or "of no recognized type or kind").
The athlete was so nondescript in person that she was barely distinguishable from the general crowd.