[{"Bold_text": "noun", "List Items": ["force or speed of movement; impetus, as of a physical object or course of events:The car gained momentum going downhill. Her career lost momentum after two unsuccessful films.", "Also calledlin?ear momen?tum.Mechanics.a quantity expressing the motion of a body or system, equal to the product of the mass of a body and its velocity, and for a system equal to the vector sum of the products of mass and velocity of each particle in the system.", "Philosophy. moment(def7) moment(def7)."]}]