| leader(noun, character, originator, hero, producer) |
| leaven(noun, reason, element, matter, source) |
| lord(spirit, master, soul, deity, god) |
| machine |
| main cause(expression, reason, importance, significance) |
| main condition(expression, reason, importance, significance) |
| main criterion(expression, reason, importance, significance) |
| main culprit(expression, reason, importance, significance) |
| main reason(expression, reason, importance, significance) |
| mainspring(noun, reason, element, matter, source) |
| major asset(expression, reason, importance, significance) |
| major cause(expression, reason, importance, significance) |
| major concern(expression, reason, importance, significance) |
| major premise(expression, reason, importance, significance) |
| major reason(expression, reason, importance, significance) |
| major term(expression, reason, importance, significance) |
| manufacturer |
| master craftsman |
| master factor(expression, reason, importance, significance) |
| matriarch(noun, originator, producer, author, founder) |