herse
A kind of gate or portcullis, having iron bars, like a harrow, studded with iron spikes, hung above gateways so that it may be quickly lowered to impede the advance of an enemy.
In the south aisle, on a slab raised on four low shafts and covered by an iron herse, is a fine coloured recumbent effigy of a bishop
Where it comes from
From Middle English hierche (“type of harrow”), from Middle French herce, herse. Doublet of hearse.
Adapted from the Wiktionary entry herse (CC BY-SA 4.0).