The Fantaisie in Chopin's works

[Kassaa]

There are some works with fantaisie in it, an impromptu, polonaise, op.49. What does the fantaisie means, what does it add to a piece?

[Derek]

I think it just means freer, not so constrained by a form. so if you see sonata-fantasie, that means its got some sonata like elements but it doesn't stick to a strict formal structure of a sonata, and sounds almost improvisatory in places.  Thats my impression of it....that may very well be "incorrect"