sub·sidence \səbˈsīdən(t)s, ˈsəbsədən-\noun (-s) Etymology: Latin subsidentia, from subsident-, subsidens (present participle of subsidere to subside) + -ia 1.: something (as a sediment in a liquid) that has subsided 2.: the act or process of subsiding : a falling, lowering, or flattening out < the subsidence of waves after a storm > < his anger underwent a quick subsidence >