[Haskell-beginners] combinator

Is there some kind soul who would elaborate somewhat on what exactly a combinator is, and the significance they have in Haskell programming? Is there anything special about the way that we use the term in a Haskell programming context? Are combinators tied into everything we do in Haskell, or is it more of a special branch of study? A year or two ago I studied some lambda calculus, and I remember some interesting (but rather theoretical) little problems involving properties of certain combinators, and how they behaved when combined with others. But in some Haskell module documentation, it seems like everything and anything is referred to as a "combinator", so I'm getting a bit confused. -- frigidcode.com indicium.us