from The American Heritage® Dictionary of the English Language, 4th Edition
- n. One that is considered ugly or unpromising at first but has the potential of becoming beautiful or admirable in maturity.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A young person who is ugly, but who is expected to become beautiful as they mature.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. an ugly or unpromising child who grows into a beautiful or worthy person
After The Ugly Duckling, a story by Hans Christian Andersen.(American Heritage® Dictionary of the English Language, Fourth Edition)
From a fairy tale of a duckling, considered ugly, that matures into a magnificent swan. (Wiktionary)