a leopard can't change its spots

ضرب المثل
a leopard can't change its spots
معنی: 

A person cannot change his/her nature or character, especially if it is bad.

هیچ کس نمی تواند شخصیت و ماهیت خود را تغییر دهد، مخصوصا اگر بد باشد.

معادل فارسی: 

نتوان شستن از زنگی سیاهی

ز ناپاکزاده مدارید امید          که زنگی به شستن نگردد سپید

مثال: 

He swears he has changed and won't hit his wife again, but we cannot believe him. A leopard can’t change its spots. We don’t want to risk his wife's life by sending her back to his house.

معنای کلمه به کلمه: 

پلنگ نمی تواند لکه های بدنش را عوض کند.

سطح، موضوع و برچسب

Oxford Advanced Learner's Dictionary

(a) leopard cannot change its spots

a leopard cannot change its ˈspots idiom

(saying) people cannot change their character, especially if they have a bad character

• You didn't really expect her to be on time, did you? A leopard can't change its spots. 

Main entry: leopard idiom