(adj) of the greatest importance, Syn.crucial, all important, of the essence, essential, Example: the all-important subject of disarmament; crucial information; in chess cool nerves are of the essence
adj. prenom. 1. of the greatest importance. the all-important subject of disarmament Syn. -- all important(predicate), crucial, essential, of the essence(predicate). [ WordNet 1.5 ]