Definitions for: Pivotal

[adj] 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"

Webster (1913) Definition: 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.

Synonyms: crucial, important, polar