Code: Cellar (technical term)
Description: It is an enclosed space having more than one‑half of its height below curb level. Usually, if a cellar has any windows, the windows are too small and too high for an adult to use as an emergency exit.
Practical Meaning: Typical legal uses for a cellar in a small home are storage, mechanical rooms (boiler, water heater), laundry, or recreational space that is not used for sleeping. A cellar that is used for sleeping or as a regular bedroom may be considered an illegal apartment or an illegal conversion by NYC agencies.
Source: cellar in NYC