dream-hole
/ˈdriːmˌhəʊl/Chiefly English regional (Gloucestershire and Yorkshire )
noun
A slit or opening in an external wall of a building.
- Apparently intended for the admission of light and air, or for defensive purposes, though N.E.D. (1897) notes: ‘Supposed (by modern archaeologists) to have been originally applied to the holes in church-towers and belfries by which the sound passed out’..
Origin
Mid 16th century; earliest use found in Churchwardens' Accounts Minchinhampton. Origin uncertain; apparently from dream + hole, on account of the sound of the bells passing through such holes in a church steeple.