Wiktionary
n. (context physics English) Half of the harmonic mean of two given masses.
Wikipedia
In physics, the reduced mass is the "effective" inertial mass appearing in the two-body problem of Newtonian mechanics. It is a quantity which allows the two-body problem to be solved as if it were a one-body problem. Note, however, that the mass determining the gravitational force is not reduced. In the computation one mass can be replaced with the reduced mass, if this is compensated by replacing the other mass with the sum of both masses. The reduced mass is frequently denoted by μ ( Greek lower case mu), although the standard gravitational parameter is also denoted by μ (and so are a number of other physical quantities as well). It has the dimensions of mass, and SI unit kg.
Usage examples of "reduced mass".
Its door had been sacrificed on Marglot to the cause of reduced mass, but Atvar H'sial moved to stand at the entrance and prevent anyone else from entering.
Not sinking continued to win the toss as he reduced mass on his suit and applied power to forward thrusters to keep going even when the ground slid away in a lumpy slurry beneath him.
More bolts flew down towards him but he was able to deflect them with his shield as he trotted back towards the reduced mass of orcs.
Shapeshifting into reduced mass is seen by a Dreen's subconscious as a threat to his existence.
Or maybe it was my reduced mass that made it seem stiff and unyielding.
So we give them that, and the space-warping fields, and the genetic engineering that created Minos and freed Carpentier from the need to eat or drink or sleep, and the weather control, and the reduced mass of people in the winds, and the engineering technology that built Infernoland itself.