  We present parallax and proper motion measurements, near-infrared spectra,
and WISE photometry for the low surface gravity L5gamma dwarf
2MASSJ035523.37+113343.7 (2M0355). We use these data to evaluate photometric,
spectral, and kinematic signatures of youth as 2M0355 is the reddest isolated L
dwarf yet classified. We confirm its low-gravity spectral morphology and find a
strong resemblance to the sharp triangular shaped $H$-band spectrum of the 10
Myr planetary-mass object 2M1207b. We find that 2M0355 is underluminous
compared to a normal field L5 dwarf in the optical and MKO J,H, and K bands and
transitions to being overluminous from 3-12 microns, indicating that enhanced
photospheric dust shifts flux to longer wavelengths for young, low-gravity
objects, creating a red spectral energy distribution. Investigating the
near-infrared color magnitude diagram for brown dwarfs confirms that 2M0355 is
redder and underluminous compared to the known brown dwarf population, similar
to the peculiarities of directly imaged exoplanets 2M1207b and HR8799bcd. We
calculate UVW space velocities and find that the motion of 2M0355 is consistent
with young disk objects (< 2-3 Gyr) and it shows a high likelihood of
membership in the AB Doradus association.
