What is "transomed"

Usage examples of "transomed".

The ground appeared to have been whipped out from under the northern half of the building, for on that side the walls sagged and a rusted railway track that had risen on a transomed ramp to its top floor had half collapsed.

All I noticed at the time was that it was a rather strange conglomeration of diapered brickwork and an array of mullioned and transomed windows, which suggested a Jacobean house, with a hipped roof and gleaming central cupola, which was more characteristic of the reign of Charles II.