Plain English Meaning
A gentle, controlled turn that takes two minutes to go all the way around in a full circle. It is the standard turn rate pilots use when flying on instruments so that turns are predictable and easy to time.
Full Definition
A turn at a rate of 3 degrees per second, which completes a full 360-degree turn in 2 minutes and a 180-degree turn in 1 minute. It is the reference turn rate used in instrument flying and is indicated by the standard-rate index marks on the turn coordinator or turn-and-slip indicator.
Context Anchor
Used in instrument flying, timed turns, and flight training when the pilot needs a predictable turn rate.