1.
[syn: pivotal, polar]
The Collaborative International Dictionary of English v.0.48:
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]
WordNet (r) 3.0 (2006):
pivotal
adj 1: 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]