Prepossession, n.
1. Preoccupation; prior possession. Hammond.
2. Preoccupation of the mind by an opinion, or impression, already formed; preconceived opinion; previous impression; bias; -- generally, but not always, used in a favorable sense; as, the prepossessions of childhood. "The prejudices and prepossessions of the country." Sir W. Scott.
Syn. -- Bent; bias; inclination; preoccupancy; prejudgment. See Bent.
Shades of meaning
Fernald has no entry of its own for prepossession; he lists it under prejudice.
Where he writes about it:
A prejudice or prepossession is grounded often on feeling, fancy, associations, etc. — from prejudice
A prepossession is always favorable, a prejudice always unfavorable, unless the contrary is expressly stated. — from prejudice