Definition
A spinning rotor supported in a set of pivoted rings (gimbals) that allow the rotor's spin axis to remain free to point in any direction in space, independent of the movement of the surrounding mounting. With three gimbals, the gyroscope has three degrees of freedom and can maintain its orientation regardless of how the aircraft pitches, rolls, or yaws around it.
Plain English
A spinning wheel held inside a frame of pivoting rings, set up so the wheel can keep pointing the same way no matter how the thing holding it tilts or turns.
Context Anchor
Seen in gyroscopic flight instrument discussions, especially when learning why attitude and heading instruments can stay stable while the aircraft moves.
Derivation
Universally mounted' comes from 'universal joint' -- a mechanical mounting that allows movement in all directions. So a universally mounted gyroscope is one mounted in a way that lets it stay free in any direction. 'Gyroscope' comes from Greek 'gyros' (circle/turn) and 'skopein' (to see) -- literally 'to see the turning,' which is exactly what these instruments help pilots do.
Why Pilots Care
This free mounting provides a stable reference for aircraft attitude and heading that does not tumble or drift during normal maneuvers.
Analogy
Think of a spinning top set inside a series of rings on swivels. You can pick up the whole frame and tilt it any direction you like, but the top keeps spinning upright in space. The frame moves; the spin stays.
Intuition Check
Do not read “universally” as “common everywhere.” Here it means the gyroscope is mounted so it can move freely in more than one direction.
Example Sentence 1
The attitude indicator uses a universally mounted gyroscope so that the rotor stays level with the horizon while the aircraft pitches and rolls around it.
Example Sentence 2
During a turn, the universally mounted gyroscope continues to indicate straight-and-level flight until the aircraft returns to wings level.