  This letter presents incontrovertible evidence that NGC5506 is a Narrow Line
Seyfert 1 (NLSy1). Our new 0.9-1.4 micron spectrum of its nucleus clearly shows
the permitted OI 1.1287 micron line (with full width at half maximum <2000
km/s) and the `1 micron FeII lines'. These lines can only originate in the
optically-thick broad line region (BLR) and, among Seyfert nuclei the latter
series of lines are seen only in NLSy1s. The obscuration to the BLR, derived
from a rough estimate of the OI 1.1287 micron / OI 8446 Angstrom ratio and from
the reddening of the near-IR Paschen lines, is A_v > 5. Together, these results
make NGC5506 the first identified case of an optically-obscured NLSy1. This new
classification helps explain its radio to X-ray properties, which until now
were considered highly anomalous. However, interesting new concerns are raised:
e.g., NGC5506 is unusual in hosting both a `type 1' AGN and a nuclear water
vapor megamaser. As the brightest known NLSy1, NGC5506 is highly suitable for
study at wavebands less affected by obscuration.
