barbican
A tower at the entrance to a castle or fortified town.
The stone part of the drawbridge with its barbican and the bartizans of the gatehouse are in good repair. […] There was a large hidden trapdoor in the floor of the barbican, which would let them into the moat after all.
A fortress at the end of a bridge.
An opening in the wall of a fortress through which the guns are levelled; a narrow loophole through which arrows and other missiles may be shot.
Two shafts of soft daylight fell across the flagged floor from the high barbacans.
A temporary wooden tower built for defensive purposes.
Where it comes from
From Old French barbacane, of uncertain origin: compare Arabic بَرْبَخ (barbaḵ, “aqueduct, sewer”), and Persian بابخانه (bâb-xâne, “gatehouse”).
Adapted from the Wiktionary entry barbican (CC BY-SA 4.0).