  The systematic study of the correlation between the experimental giant dipole
resonance (GDR) width and the average deformation <\beta> of the nucleus at
finite excitation is presented for the mass region A ~ 59 to 208. We show that
the width of the GDR (\Gamma) and the quadrupole deformation of the nucleus do
not follow a linear relation, as predicted earlier, due to the GDR induced
quadrupole moment and the correlation also depends on the mass of the nuclei.
The different empirical values of <\beta> extracted from the experimental GDR
width match exceptionally well with the thermal shape fluctuation model. As a
result, this universal correlation between <\beta> and \Gamma provides a direct
experimental probe to determine the nuclear deformation at finite temperature
and angular momentum in the entire mass region.
