• (n.) The doctrine that the soul is preexistent to the body, and is infused into it at conception or birth; -- opposed to tradicianism and creationism.
In·fu'sion·ism noun The doctrine that the soul is preexistent to the body, and is infused into it at conception or birth; -- opposed to traducianism and creationism . 
the doctrine that the soul existed in a previous state and is infused into the body at conception or birth.