  We obtain subnatural linewidth (i.e. $<\Gamma$) for probe absorption in
room-temperature Rb vapor using electromagnetically induced transparency (EIT)
in a $\Lambda$ system. For stationary atoms, the EIT dip for a resonant control
laser is as wide as the control Rabi frequency $\Omega_c$. But in thermal
vapor, the moving atoms fill the transparency band so that the final EIT dip
remains subnatural even when $\Omega_c > \Gamma$. We observe linewidths as
small as $\Gamma/7$ in the $D_2$ line of Rb.
