Plain English Meaning
The airplane's nose is pointing down below the horizon. Left alone, the airplane will descend and speed up.
Full Definition
An aircraft attitude in which the nose is pitched below the horizon, typically resulting in a descent and an increasing airspeed if uncorrected. In the context of unusual attitude recovery, a nose-low attitude is one where the pitch is significantly below level flight and prompt corrective action is required.
Context Anchor
Used during recovery from unusual attitudes, stalls, or other situations where the airplane’s nose position must be corrected promptly.