Exigency, n.;pl. Exigencies.
Etymology: [LL. exigentia: cf. F. exigence.]
The state of being exigent; urgent or exacting want; pressing necessity or distress; need; a case demanding immediate action, supply, or remedy; as, an unforeseen exigency. "The present exigency of his affairs." Ludlow.
Syn. -- Demand; urgency; distress; pressure; emergency; necessity; crisis.
Shades of meaning
Fernald has no entry of its own for exigency; he lists it under necessity.
He lists it without comment; the entries above explain its neighbors.