  Eclipsing systems of massive stars allow one to explore the properties of
their components in great detail. We perform a multi-wavelength, non-LTE
analysis of the three components of the massive multiple system $\delta$ Ori A,
focusing on the fundamental stellar properties, stellar winds, and X-ray
characteristics of the system. The primary's distance-independent parameters
turn out to be characteristic for its spectral type (O9.5 II), but usage of the
${\rm \it Hipparcos}$ parallax yields surprisingly low values for the mass,
radius, and luminosity. Consistent values follow only if $\delta$ Ori lies at
about twice the ${\rm \it Hipparcos}$ distance, in the vicinity of the
$\sigma$-Orionis cluster. The primary and tertiary dominate the spectrum and
leave the secondary only marginally detectable. We estimate the V-band
magnitude difference between primary and secondary to be $\Delta V \approx
2.\!\!^{\rm m}8$. The inferred parameters suggest the secondary is an early
B-type dwarf ($\approx$ B1 V), while the tertiary is an early B-type subgiant
($\approx$ B0 IV). We find evidence for rapid turbulent velocities ($\sim 200$
km ${\rm s}^{-1}$) and wind inhomogeneities, partially optically thick, in the
primary's wind. The bulk of the X-ray emission likely emerges from the
primary's stellar wind ($\log L_{\text{X}} / L_{\text{Bol}} \approx -6.85$),
initiating close to the stellar surface at $R_0 \sim 1.1\,R_*$. Accounting for
clumping, the mass-loss rate of the primary is found to be $\log \dot{M}
\approx -6.4\,[M_\odot\,{\rm yr}^{-1}]$, which agrees with hydrodynamic
predictions, and provides a consistent picture along the X-ray, UV, optical and
radio spectral domains.
