piv·ot·al I. \ˈpivəd.əl, -ətəl\adjective Etymology: International Scientific Vocabulary pivot (I) + -al 1. a.: of or relating to a pivot < correct pivotal dimensions > b.: constituting or functioning as a pivot < a pivotal shaft > 2.: that vitally affects the activity or development or course of something : central in importance, function, influence, or effect < holds a pivotal position > < one of the great pivotal points of the war — S.L.A.Marshall > II. noun (-s) : something that is pivotal