Wiktionary
alt. (context theology philosophy sometimes capitalized English) An initial cause from which all other causes and effects follow. n. (context theology philosophy sometimes capitalized English) An initial cause from which all other causes and effects follow.
WordNet
n. a self-caused agent that is the cause of all things; "God is the first cause" [syn: prime mover, primum mobile]
Usage examples of "first cause".
For in the first cause, if you do not declare, you shall be a prey to him who overcomes, and it will be a pleasure and satisfaction to him that is conquered to see you his fellow-sufferer.
No matter how deep you dug, you could not come up with a First Cause.
If we reflect upon the first cause of the ruin of the Roman empire, it will be found to begin at their entertaining the Goths into their service, for thereby they weakened and enervated their own native courage, and, as it were, transfused it into them.
Knowledge of necessities is desirous:-Deliberation is but a sorry disatisfaction-a first cause of illusions, harnessing man to a mass of half-realized desires.
Paget told him, 'Unless Your Grace will debate with other men and hear them say their opinions, that will ensue whereof I would be right sorry, and Your Grace shall have first cause to repent.