case of need
climacteric
clutch
compulsion
constraint
contingency
convergence of events
crisis
critical juncture
critical point
crossroads
crucial period
crunch
demand
demandingness
difficulty
dire necessity
distress
drive
emergency
exigence
extremity
high pressure
hinge
immediacy
imperative
imperativeness
importunacy
importunateness
importunity
impulse
impulsion
insistence
juncture
matter of necessity
necessity
need
pass
persistence
pertinaciousness
pertinacity
pinch
predicament
press
pressingness
exigent
exiguity
exiguous
annals
ascendency
catastrophe
commencement
complication
continuance
disadvantage
embarrassment
hardship
inconvenience
limitation
ordeal
peril
perplexity
significance
urgency
vicissitudes