Plain English Meaning
A set agreed way of doing each task in the cockpit, written down so every pilot does it the same way every flight.
Full Definition
Standard operating procedures are written, pre-established methods for accomplishing routine flight tasks in a consistent, repeatable way. They specify how a crew or pilot will configure the aircraft, run checklists, communicate, and respond to normal and abnormal situations, so that the same task is performed the same way every time regardless of who is flying.
Context Anchor
Seen in risk management discussions, flight school rules, cockpit routines, and the PAVE checklist when considering whether outside pressure might tempt a pilot to skip the normal safe way of doing something.