impact /ˈɪmpækt/noun 4/ɪmˈpækt/ verb 4forms 3 noun4 •The striking of one body against another; collision. •(figurative) an important or strong effect, one that changes someone or something in a clear wayHis friend's opinion had an impact on his decision.Our choice of concrete will have a tremendous impact on the building's mechanical performance. •A forced impinging.His spine had an impingement; L4 and L5 made impact, which caused numbness in his leg. •The force or energy of a collision of two objects.The hatchet cut the wood on impact. impact /ɪmˈpækt/ verb4 •To collide or strike, the act of impinging.When the hammer impacts the nail, it bends. •(nonstandard, figurative) To significantly or strongly influence or affect; to have an impact on.I can make the changes, but it will impact the schedule. •To compress; to compact; to press into something or pack together.The footprints of birds do not impact the soil in the way those of dinosaurs do. •(rare) To stamp or impress onto something.Ideas impacted on the mind. formsimpacted · impacting · impacts