  We present far-ultraviolet spectra of the Seyfert 1 galaxy Mrk 509 obtained
in 1999 November with the Far Ultraviolet Spectroscopic Explorer (FUSE). Our
data span the observed wavelength range 915-1185 A at a resolution of ~20 km/s.
The spectrum shows a blue continuum, broad OVI 1032,1038 emission, and a broad
CIII 977 emission line. Superposed on these emission components, we resolve
associated absorption lines of OVI 1032,1038, CIII 977, and Lyman lines through
Lzeta. Seven distinct kinematic components are present, spanning a velocity
range of -440 to +170 km/s relative to the systemic velocity. The absorption is
clustered in two groups, one centered at -370m km/s and another at the systemic
velocity. The blue-shifted cluster may be associated with the extended line
emission visible in deep images of Mrk 509 obtained by Phillips et al. Although
several components appear to be saturated, they are not black at their centers.
Partial covering or scattering permits ~7% of the broad-line or continuum flux
to be unaffected by absorption. Of the multiple components, only one has the
same ionization state and column density as highly ionized gas that produces
the OVII and OVIII ionization edges in X-ray spectra of Mrk 509.
  This paper will appear in a special issue of Astrophysical Journal Letters
devoted to the first scientific results from the FUSE mission.
