A loose point is a vertical support that allows for horizontal displacements.
Possible Scheme of Bridge with Fixed and Loose Points
In contrast to fixed points (1 and 3), loose points (2) do not transfer any horizontal forces to adjacent structures. This means, for example, that roller supports are displaceable in the longitudinal direction of a bridge. Thus, the linear expansion due to temperature can be compensated without the necessity to enter additional loads into the structure.