(n.) Exigency.

case of need climacteric clutch compulsion constraint contingency convergence of events crisis critical juncture critical point crossroads crucial period crunch demandingness dire necessity drive emergency exigence extremity high pressure hinge immediacy imperative imperativeness importunacy importunateness importunity impulse impulsion insistence matter of necessity pass persistence pertinaciousness pertinacity pinch predicament press pressingness pressure push rash impulse rub strait stress tension turn turning turning point urge urgency urgent need