noun. 
                    Lack of activity; sluggishness; passiveness; inertness.
                  
                
                  
                    noun. 
                    In physics, that property of matter by virtue of which it retains its state of rest or of uniform rectilinear motion so long as no foreign cause changes that state. Also called vis inertiæ (force of inertia).
                  
                
                  
                    noun. 
                    In medicine, want of activity; sluggishness: a term especially applied to the condition of the uterus when it does not contract properly in parturition.
                  
                
                  
                    noun. 
                    With regard to a plane or point, the sum of the elements of mass each multiplied by the square of its distance from the given plane or point.