Plain English Meaning
Extra weight carried on purpose to keep the airplane balanced within safe limits.
Full Definition
Weight added to an aircraft, either permanently or temporarily, to bring its center of gravity within approved limits or to maintain a desired weight distribution.
Context Anchor
Seen in loading and balance discussions, including when a nose baggage compartment is used to help keep the airplane within its allowed balance range.
Derivation
From an old Scandinavian word meaning 'bare load' -- weight carried not for its own sake but to steady the vessel. The same idea originally kept ships upright; in aircraft it keeps the loaded airplane within its center of gravity range.
Why Pilots Care
Placing the correct amount of ballast prevents the center of gravity from moving outside limits, which would reduce or .