Zouk, or "Brazilian Zouk" is a dance originating in Brazil from Lambada.  It's only about 30 years old.

It's kind of like Salsa or Bachata, but more flowy and sometimes people call it "sensual".  

Unlike other dances, Zouk happily accepts influences from many dance styles, and therefore a "Zouk" dance can feel and look very different from one dance to another.  

See below for some examples.