  We present a HST/STIS spectroscopic and optical/radio imaging study of the
Seyfert NGC 2110 aiming to measure the dynamics and understand the nature of
the nuclear outflow in the galaxy. Previous HST studies have revealed the
presence of a linear structure in the Narrow-Line Region (NLR) aligned with the
radio jet. We show that this structure is strongly accelerated, probably by the
jet, but is unlikely to be entrained in the jet flow. The ionisation properties
of this structure are consistent with photoionisation of dusty, dense gas by
the active nucleus. We present a plausible geometrical model for the NLR,
bringing together various components of the nuclear environment of the galaxy.
We highlight the importance of the circum-nuclear disc in determining the
appearance of the emission line gas and the morphology of the jet. From the
dynamics of the emission line gas, we place constraints on the accelerating
mechanism of the outflow and discuss the relative importance of radio source
synchrotron pressure, radio jet ram pressure and nuclear radiation pressure in
accelerating the gas. While all three mechanisms can account for the energetics
of the emission line gas, gravitational arguments support radio jet ram
pressure as the most likely source of the outflow.
