Plain English Meaning
An entry on a pilot certificate that says which group of aircraft you are allowed to fly within a broader category. For airplanes, it tells you whether you are qualified for one engine or more than one, and whether the aircraft operates from land or water.
Full Definition
A subdivision of an airman certificate category that identifies a group of aircraft within that category sharing similar operating characteristics. For airplanes, the class ratings are single-engine land, single-engine sea, multiengine land, and multiengine sea.
Context Anchor
Seen when discussing pilot certificates, aircraft checkout requirements, and moving from one kind of airplane to another.
Derivation
From Latin classis, meaning a group or division. The word ‘class’ in keeps that idea: a grouping of aircraft that share enough common handling traits to be flown under one qualification.