|daləm|be(ə)rz- noun
Usage: usually capitalized A
Etymology: after Jean LeRond d'Alembert died 1783 French mathematician, its formulator
: a principle in mechanics : the reaction due to the inertia of an accelerated body (as a baseball) is equal and opposite to the force causing the acceleration (as the blow of a bat upon the baseball) and results in a condition of kinetic equilibrium — compare law of motion 3