To slide in an uncontroled way, usually as the result of an accident. Often, but not always used with reference to an inanimate object.
A small object accidentally kicked whle resting on a tiled floor might 'skitter' across the tiles.
Supposedly from skite, itself derived from old norse skjóta meaning shoot, as opposed to the other skite derived from skíta meaning shite. (Hence it's other common meaning!)
The hub-cap slid and skittered across the cobbled street, and disapeared through the broken storm drain grating.