Broadly, the belief that people who speak different languages perceive and think about the world quite differently, their worldviews being shaped or determined by the language of their culture (a notion rejected by social determinists and by realists). The stance is loosely derived from the theories of Benjamin Lee Whorf and his teacher Edward Sapir in the 1930s, though subsequent interpretations often bear little relation to their actual claims. In its most extreme version the hypothesis can be described as relating two associated principles: linguistic determinism and linguistic relativism. While few linguists would accept the hypothesis in its strong, extreme, or deterministic form, many now accept a weak, more moderate, or limited Whorfianism, namely that the ways in which we see the world may be influenced to some extent by the kind of language we use. See also mould theory.
http://www.aber.ac.uk/media/Documents/short/whorf.html The Sapir-Whorf hypothesis