A loan shark
is a person who lends money to somebody (usually a very poor
, very desperate
person) with the promise of receiving the original sum
and X amount of interest
in return. X can be anything from 1%
depending on the shark
Violence and intimidation would be the main weapons of a loan shark in order for the money to be returned, and when that fails, the violence usually spreads to the person's closest family and friends.
It's a very nasty business and has been going on for years in the poorest parts of the world.