Motor Inductance
It is the magnetic energy storage capability of the motor winding, expressed in millihenries. In a PWM-driven motor it is the main factor that determines how smooth the current will be: the larger the inductance, the smaller the current ripple.
Winding inductance acts as a natural filter against PWM pulses. Because current cannot change instantly, the motor responds to the average of the chopped pulses. This is the fundamental reason why speed control with PWM is possible at all.
Values differ greatly by motor type. In large, many-turn brushed DC motors inductance is typically in the range of a few millihenries, while in small ironless-rotor motors it can fall below a hundred microhenries. Low-inductance motors draw far greater ripple at the same frequency and therefore demand a high switching frequency; otherwise the motor heats up needlessly.
The consequence on the application side is that a driver will not behave the same way with every motor. A module running quiet and cool on one specific motor does not mean it will give the same result on a very different motor. Re-measuring the driver temperature and the current it draws after you change the motor is an overlooked but important step.
Context where this term is used: DC Motor Driver Selection Guide