  IGR J18214-1318, a Galactic source discovered by the International Gamma-Ray
Astrophysics Laboratory, is a high-mass X-ray binary (HMXB) with a supergiant
O-type stellar donor. We report on the XMM-Newton and NuSTAR observations that
were undertaken to determine the nature of the compact object in this system.
This source exhibits high levels of aperiodic variability, but no periodic
pulsations are detected with a 90% confidence upper limit of 2% fractional rms
between 0.00003-88 Hz, a frequency range that includes the typical pulse
periods of neutron stars (NSs) in HMXBs (0.1-10$^3$ s). Although the lack of
pulsations prevents us from definitively identifying the compact object in IGR
J18214-1318, the presence of an exponential cutoff with e-folding energy
$\lesssim30$ keV in its 0.3-79 keV spectrum strongly suggests that the compact
object is an NS. The X-ray spectrum also shows a Fe K$\alpha$ emission line and
a soft excess, which can be accounted for by either a partial-covering absorber
with $N_{\mathrm{H}}\approx10^{23}$ cm$^{-2}$ which could be due to the
inhomogeneous supergiant wind, or a blackbody component with
$kT=1.74^{+0.04}_{-0.05}$ keV and $R_{BB}\approx0.3$ km, which may originate
from NS hot spots. Although neither explanation for the soft excess can be
excluded, the former is more consistent with the properties observed in other
supergiant HMXBs. We compare IGR J18214-1318 to other HMXBs that lack
pulsations or have long pulsation periods beyond the range covered by our
observations.
