Nitrenes are a highly reactive, yet fundamental compound class. They possess a mono-valent nitrogen atom and usually a short life span, typically in the nanosecond range. Here, we report on the synthesis of a stable nitrene by photolysis of the arylazide MSFluindN3 (1), which gave rise to the quantitative formation of the arylnitrene MSFluindN (2) (MSFluind = dispiro[fluorene-9,3'-(1',1',7',7'-tetramethyl-s-hydrindacen-4'-yl)-5',9''-fluorene]), that remains unchanged for at least 3 days when stored under argon atmosphere at room temperature. The extraordinary life span permitted the full characterization of 2 by single crystal x-ray crystallography, EPR spectroscopy and SQUID magnetometry, which supported a triplet ground state. Theoretical simulations suggest in addition to the kinetic stabilization conferred by the bulky MSFluind aryl substituent, that electron delocalization across the central aromatic ring contributes to the electron stabilization of 2.