Definition
An electric motor designed to operate on either alternating current (AC) or direct current (DC) power. It uses a wound armature and field coils connected in series, which allows it to develop torque regardless of the direction of current flow.
Plain English
A small electric motor that runs on either AC or DC power. The same motor works no matter which type of electricity you feed it.
Context Anchor
Seen in aircraft electrical-system study and maintenance discussions, especially when comparing different types of electric motors.
Derivation
Called 'universal' because it works universally with both AC and DC power, unlike most motors which are designed for one or the other.
Why Pilots Care
Allows critical flight controls and systems to keep working when the aircraft switches between AC and DC power sources.
Intuition Check
Universal does not mean the motor fits every aircraft or every job. Here it means the motor can operate on either direct current or single-phase alternating current when it is designed that way.
Example Sentence 1
The cabin fan uses a universal motor, so it operates on either the aircraft's DC bus or external AC power.
Example Sentence 2
During preflight the technician checked that the universal motor turned smoothly on both AC and DC test power.