  We investigate the nature of the complex retarded potential of a heavy
quarkonium moving in a hot and dense static deconfined nuclear medium. The
well-known concept of the retarded potential in electrodynamics is extended to
the context of the heavy-quark by modifying the static vacuum Cornell potential
through Lorentz transformation to the static frame of the medium. The resulting
potential in the vacuum is further corrected to incorporate the screening
effect offered by the thermal medium. To do so, the retarded Cornell potential
is modified by the dielectric function of the static quark-gluon plasma (QGP)
medium. We present the numerical results for the real and imaginary parts of
the potential along with the analytical expression of the potential
approximated by a small velocity limit. Finally, we present the thermal width
of quarkonia in the QGP medium derived using the imaginary part of the
potential and study its dependence on velocity and temperature.
