Adjective
1. of extreme importance; vital to the resolution of a crisis;
"a crucial moment in his career""a crucial election""a crucial issue for women"2. having crucial relevance;
"crucial to the case""relevant testimony"3. of the greatest importance;
"the all-important subject of disarmament""crucial information""in chess cool nerves are of the essence"4. having the power or quality of deciding;
"the crucial experiment""cast the deciding vote""the determinative (or determinant) battle"