In previous work the parameter of glassiness was introduced to distinguish between a liquid and a glass, using a formal analogy with the quantum Bose system. The glassiness is defined in such a way that it is unity in a frozen system and less than one in a liquid. In the present letter we revise first the results obtained for the glassiness in a hard sphere liquid as a function of the density. Then we investigate the influence of an attractive potential by obtaining the glassiness as a function of the density, temperature and the attractive tail when a square well potential is added to the hard core.