Sine qua non,

Definition of Sine qua non:

1. Absolutely essential or indispensable. Latin for, without which not.

Synonyms of Sine qua non

Bench mark, Boundary condition, Cardinal point, Catch, Chief thing, Clause, ■■■■■■, Condition, Core, Cornerstone, Crisis, Critical point, Crux, Donnee, Escalator clause, Escape clause, Escape hatch, Essence, Essential, Essential matter, Fine print, Fundamental, Gist, Given, Gravamen, Great point, Grounds, Heart, High point, Important thing, Issue, Joker, Kernel, Keystone, Kicker, Landmark, Limiting condition, Main point, Main thing, Material point, Meat, Milestone, Must, Necessity, Nub, Obligation, Parameter, Pith, Pivot, Prerequisite, Provision, Provisions, Proviso, Real issue, Requirement, Requisite, Salient point, Saving clause, Small print, Specification, Stipulation, String, Substance, Substantive point, Terms, The bottom line, The point, Turning point, Ultimatum, Whereas