  We present high-resolution Large Binocular Telescope LBTI/LMIRcam images of
the spectroscopic and astrometric binary NO UMa obtained as part of the LBTI
Exozodi Exoplanet Common Hunt (LEECH) exoplanet imaging survey. Our H, K$_s$,
and L'-band observations resolve the system at angular separations <0.09". The
components exhibit significant orbital motion over a span of ~7 months. We
combine our imaging data with archival images, published speckle interferometry
measurements, and existing spectroscopic velocity data to solve the full
orbital solution and estimate component masses. The masses of the K2.0$\pm$0.5
primary and K6.5$\pm$0.5 secondary are 0.83$\pm$0.02 M$_{\odot}$ and
0.64$\pm$0.02 M$_{\odot}$, respectively. We also derive a system distance of d
= 25.87$\pm$0.02 pc and revise the Galactic kinematics of NO UMa. Our revised
Galactic kinematics confirm NO UMa as a nuclear member of the ~500 Myr old Ursa
Major moving group and it is thus a mass and age benchmark. We compare the
masses of the NO UMa binary components to those predicted by five sets of
stellar evolution models at the age of the Ursa Major group. We find excellent
agreement between our measured masses and model predictions with little
systematic scatter between the models. NO UMa joins the short list of nearby,
bright, late-type binaries having known ages and fully characterized orbits.
