bench mark cardinal point chief thing climacteric climax clutch contingency convergence of events core cornerstone crisis critical juncture critical point crossroads crucial period crunch crux culmination emergency essence essential essential matter exigency extremity fundamental gist gravamen great point heart high point hinge important thing issue kernel keystone landmark main point main thing material point meat milestone moment of truth nub pass peak pinch pith pivot push real issue rub salient point sine qua non strait substance substantive point the bottom line the point turn zero hour