According to my knowledge steadicam was a fluent movement of camera ?

According to wikipedia.org steadicam can be defined as;

A stabilizing mount for a motion picture camera, which mechanically isolates the operator's movement from the camera, allowing a very smooth shot even when the operator is moving quickly over an uneven surface. Informally, the word may also be used to refer to the combination of the mount and camera.

So it appears that steadicam is a mount for a camera in which allows for a more stabilised image. However steadicams can often be expensive.

The image stabilisation is a useful feature found on camcorders that can be used an alternative to using a steadicam. It works by stabilising the image to reduce blur and is useful when conducting various camera movements such as a track in.

Alternatively camera shake can be reduced in editing with the use of such programs as After Affects which feature this option to do so.

As seen on the following slide in Final Cut, image can be stabilised. It is a simple and effective process that will improve the quality of our short film.