| turning point(expression, moment, influence, reason, importance) |
| leading cause(expression, reason, importance, significance) |
| root motive(expression, reason, importance, significance) |
| basic cause(expression, reason, importance, significance) |
| basic condition(expression, reason, importance, significance) |
| basic premise(expression, reason, importance, significance) |
| basic prerequisite(expression, reason, importance, significance) |
| basic term(expression, reason, importance, significance) |
| center piece(expression, reason, importance, significance) |
| central element(expression, reason, importance, significance) |
| chief criterion(expression, reason, importance, significance) |
| chief reason(expression, reason, importance, significance) |
| controlling factor(expression, reason, importance, significance) |
| core driver(expression, reason, importance, significance) |
| critical factor(expression, reason, importance, significance) |
| crucial component(expression, reason, importance, significance) |
| decisive factor(expression, reason, importance, significance) |
| determinant factor(expression, reason, importance, significance) |
| dominant cause(expression, reason, importance, significance) |
| dominant factor(expression, reason, importance, significance) |