Plain English Meaning
A nautical mile is the standard distance unit used in flying. It is a bit longer than a regular (statute) mile — roughly 1.15 statute miles — and it is tied to the shape of the Earth, which is why pilots and sailors use it instead of regular miles.
Full Definition
A unit of distance used in aviation and marine navigation, equal to 1,852 meters or approximately 6,076 feet. One nautical mile corresponds to one minute of arc of latitude along any meridian of the Earth, which is what makes it the natural unit for navigation on a globe.
Context Anchor
Seen on aviation charts, in airspace diagrams, and in descriptions such as how far controlled airspace extends from an airport.
Derivation
The word comes from the Latin nauticus, meaning 'relating to ships,' which itself traces to the Greek nautes, 'sailor.' The unit was developed for sea navigation because it lined up cleanly with the Earth's coordinate — one minute of latitude equals one nautical mile. Aviation adopted it for the same reason: it makes and navigation simpler long distances.