  The winds of massive stars have an impact on stellar evolution and on the
surrounding medium. The maximum speed reached by these outflows, the terminal
wind speed, is a global wind parameter and an essential input for models of
stellar atmospheres and feedback. With the arrival of the ULLYSES programme, a
legacy UV spectroscopic survey with HST, we have the opportunity to quantify
the wind speeds of massive stars at sub-solar metallicity (in the Large and
Small Magellanic Clouds, 0.5Z and 0.2Z) at an unprecedented scale. We
empirically quantify the wind speeds of a large sample of OB stars, including
supergiants, giants, and dwarfs at sub-solar metallicity. Using these
measurements, we investigate trends of terminal wind speed with a number of
fundamental stellar parameters, namely effective temperature, metallicity, and
surface escape velocity. We empirically determined the terminal wind speed for
a sample of 149 OB stars in the Magellanic Clouds either by directly measuring
the maximum velocity shift of the absorption component of the Civ 1548-1550
line profile, or by fitting synthetic spectra produced using the Sobolev with
exact integration method. Stellar parameters were either collected from the
literature, obtained using spectral-type calibrations, or predicted from
evolutionary models. We find strong trends of terminal wind speed with
effective temperature and surface escape speed when the wind is strong enough
to cause a saturated P Cygni profile in Civ 1548-1550. We find evidence for a
metallicity dependence on the terminal wind speed proportional to Z^0.22+-0.03
when we compared our results to previous Galactic studies. Our results suggest
that effective temperature rather than surface escape speed should be used as a
straightforward empirical prediction of terminal wind speed and that the
observed metallicity dependence is steeper than suggested by earlier works.
