| primary objective(expression, importance, aim, purpose) |
| primary target(expression, importance, aim, purpose) |
| primary task(expression, importance, aim, purpose) |
| prime objective(expression, importance, aim, purpose) |
| principal purpose(expression, importance, aim, purpose) |
| leading cause(expression, reason, importance, significance) |
| basic cause(expression, reason, importance, significance) |
| basic condition(expression, reason, importance, significance) |
| basic prerequisite(expression, reason, importance, significance) |
| basic term(expression, reason, importance, significance) |
| bottom line(expression, reason, importance, significance) |
| break point(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) |