Loan Sharks

[cjb3]

I started watching a Korean drama series yesterday evening, "쩐의 전쟁" which, after one episode, I must rate as the single most depressing movie ever made (but very interesting).

My question deals with a word that I cannot find in the dictionary, but is referred to in the English subtitle. "Loan Shark" I heard as 사지 or 사치 . My Korean wife thought it was 사채, although she was not familiar with the term (she's a musician, not a businessperson).

My guess is that it was "사채" (私債); however, the dictionary defines this only as "private loan," which hardly indicates the nasty and brutal activity commonly considered to be "loan sharking." Is that the correct word? If so, is there any llinguistic distinction between a "loan shark" and one who lends money privately upon reasonable terms and without breaking kneecaps?

[manyakumi]

My guess is that it was "사채" (私債); however, the dictionary defines this only as "private loan," which hardly indicates the nasty and brutal activity commonly considered to be "loan sharking." Is that the correct word? If so, is there any llinguistic distinction between a "loan shark" and one who lends money privately upon reasonable terms and without breaking kneecaps?

I guess it must be 사채(私債) as you mentioned.
The word 사채 itself isn't related on any nasty or brutal activities though,
it reminds most people in Korea of those negative images.

Literally,
고리대금업자(高利貸金業者:A business person who lends money in high rates of interest) is the word for "Loan shark".