from The American Heritage® Dictionary of the English Language, 4th Edition
- transitive v. To endow with a soul.
- transitive v. To place, receive, or cherish in the soul.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- v. To give a soul or place in the soul.
from the GNU version of the Collaborative International Dictionary of English
- transitive v. To indue or imbue (a body) with soul.
from The Century Dictionary and Cyclopedia
- To endow or imbue with a soul.
Sorry, no etymologies found.
But those who do and who are also evolutionists (such as CS Lewis), typically argue that God chose to "ensoul" the creatures we now describe as human beings at some point in their evolutionary history.
Thus it comes about that this kosmos, lit with many lights, gleaming in its souls, receives still further graces, gifts from here and from there, from the gods of the Supreme, and from those other Intellectual-Principles whose nature it is to ensoul.
-- Outwardly there was pomp, stately manners, pageantry, high magnificence; inwardly, a burning-up of the national imagination to ensoul it.
They are found in all regions, and they ensoul the energies of Nature.
Consciousnesses which ensoul the force and matter  which is Nature,
To all the feebleness of infancy His majestic powers bow themselves, letting but little play forth on the tender forms they ensoul.
Perhaps it the angels that come and ensoul the little guy just before he is sufficiently smart to realize it.
#82 ensoul : I am not a lesbian but I would love another wife.
#63 ensoul, I just checked out your website, your work is amazing!
doesn't tell Buffy that Willow is attempting to re-ensoul Angel season 2