Actually, definition of 덩치 is the opposite of someone's height(="키") 키 only presents someone's height but 덩치 presents volume of his/her body. Here are "덩치" in Example Sentences 규리는 덩치가 큰 여자애다. = 규리 is a big girl 하림이는 덩치가 작다. = 하림 is small But 덩치 also can be used when you called someone who is big. Like a nickname However if you call someone 덩치, He/She wouldn't happy about it. It's little bit offenssive. It sounds he/she is a big, stupid, scary, dull, slow person. and plus most Koreans tend to think 덩치 is not cute. Hopefully my answer will help you! + More example sentences and some awkward sentences - 존은 덩치다.(John is 덩치.) = X 덩치 can't be used like this. It's awkward. But You can say, - 존은 덩치가 크다. (John is big.) - 존의 별명은 '덩치'이다. ("덩치" is John's nickname.) - 덩치도 크면서 귀여운척 하지마. (Don't pretend to be cute. You are so BIG.) - 너희 강아지는 우리 강아지보다 덩치가 작다. (Your puppy is smaller than my puppy.) 덩치 can be used to person, animal. It's awkward using with non-living things like table, apartment etc. - 네 책은 덩치가 크다. = X