having or showing excessive or compulsive concern; -- used with with.

having or showing excessive or compulsive concern with something; "became more and more haunted by the stupid riddle"; "was absolutely obsessed with the girl"; "got no help from his wife who was preoccupied with the children"; "he was taken up in worry for the old woman"

Vexed by an evil spirit, like the Gadarene swine and other critics. Obsession was once more common than it is now. Arasthus tells of a peasant who was occupied by a different devil for every day in the week, and on Sundays by two. They were frequently seen, always walking in his shadow, when he had one, but were finally driven away by the village notary, a holy man; but they took the peasant with them, for he vanished utterly. A devil thrown out of a woman by the Archbishop of Rheims ran through the trees, pursued by a hundred persons, until the open country was reached, where by a leap higher than a church spire he escaped into a bird. A chaplain in Cromwell's army exorcised a soldier's obsessing devil by throwing the soldier into the water, when the devil came to the surface. The soldier, unfortunately, did not.

Obsessed is a thriller novel by Christian author Ted Dekker.

influenced or controlled by a powerful force such as a strong emotion.