bell gable

from The Century Dictionary.

• noun The continuation upward of a portion of a wall terminated by a small gable, and pierced to receive one or more bells. Such a feature sometimes surmounts the apex of a church-gable.
• noun Any gable when the wall composing it is pierced for bells.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun an extension of a gable that serves as a bell cote