In cycling, float is the degree to which you are able to rotate your feet on the pedals along the horizonal plane (in other words, rotation around around the y axis or rotation on the tops of the pedals). This ability is normally represented in "degrees of float". To be absolutely unable to rotate your feet would be to have zero float. Most clipless pedals have somewhere between 4 and 8 degrees of float.

Some float is generally desired for anyone without absolutely perfect pedalling biomechanics, as it is easier on the knees.