Exacting or requiring immediate aid or action; pressing; critical.

requiring precise accuracy; "an exacting job"; "became more exigent over his pronunciation"

Exigency; pressing necessity; decisive moment.

demanding attention; "clamant needs"; "a crying need"; "regarded literary questions as exigent and momentous"- H.L.Mencken; "insistent hunger"; "an instant need"

The name of a writ in proceedings before outlawry.

a problem perceived as important because it threatens society, compelling the search for a solution