ugly duckling
US /ˈʌɡ.li ˈdʌk.lɪŋ/
UK /ˈʌɡ.li ˈdʌk.lɪŋ/

1.
patinho feio
a person or thing that is initially unattractive or unpromising but eventually becomes beautiful or successful
:
•
She was an ugly duckling in high school, but she grew up to be a stunning model.
Ela era um patinho feio no ensino médio, mas cresceu e se tornou uma modelo deslumbrante.
•
The old building was considered an ugly duckling, but after renovation, it became the most beautiful one in the city.
O antigo edifício era considerado um patinho feio, mas após a renovação, tornou-se o mais bonito da cidade.