'Pivotal' definitions:

Definition of 'pivotal'

From: WordNet
adjective
Being of crucial importance; "a pivotal event"; "Its pivotal location has also exposed it to periodic invasions"- Henry Kissinger; "the polar events of this study"; "a polar principal" [syn: pivotal, polar]

Definition of 'Pivotal'

From: GCIDE
  • Pivotal \Piv"ot*al\, a. Of or pertaining to a pivot or turning point; belonging to, or constituting, a pivot; of the nature of a pivot; as, the pivotalopportunity of a career; the pivotal position in a battle. [1913 Webster]