What is Azeotrope?

Azeotrope:

An azeotrope  is a mixture of two or more liquids in such a way that its components cannot be altered by simple distillation.This happens because, when an azeotrope is boiled, the vapor has the same proportions of constituents as the unboiled mixture.
Because their composition is unchanged by distillation, azeotropes are also called (especially in older texts) constant boiling mixtures. The word azeotrope is derived from the Greek words ζέειν (boil) and τρόπος (turning) combined with the prefix α- (no) to give the overall meaning, "no change on boiling".