If you say that someone, especially a child, is an ugly duckling, you mean that they are unattractive or awkward now, but will probably develop into an attractive and successful person.
She was a shy, ugly duckling of a child.
ugly duckling in British English
noun
a person or thing, initially ugly or unpromising, that changes into something beautiful or admirable
Word origin
an allusion to The Ugly Duckling, a story by Hans Christian Andersen
ugly duckling in American English
a very plain child or unpromising thing that in time becomes or could become beautiful, admirable,important, etc.
Word origin
from a story by Andersen about a supposed ugly duckling that turns out to be a swan
Examples of 'ugly duckling' in a sentence
ugly duckling
Talk about transforming from an ugly duckling into a glorious swan.
The Sun (2015)
But this ugly duckling is worth plumping for.
The Sun (2015)
You've said previously that you felt like an ugly duckling when you were growing up.
The Sun (2012)
Where once it was an ugly duckling, it is now an elegant swan.
Times, Sunday Times (2006)
Normandy's ugly duckling has come of age.
Times, Sunday Times (2014)
I feel like the ugly duckling nobody wants.
The Sun (2006)
I played the ugly duckling that didn't fit in.
Times, Sunday Times (2016)
The trainee teacher said: 'I was an ugly duckling.
The Sun (2011)
Is there any way I can get out of this situation without anyone discovering that the love of my life is the original ugly duckling?
Times, Sunday Times (2009)
An ugly duckling can be made into a swan and, if the location is right, you should recoup your investment and more.