machicolation
/mæˌtʃɪkəʊˈleɪʃən/noun
1- (in medieval fortifications) an opening between the supporting corbels of a projecting parapet or the vault of a gate, through which stones or burning objects could be dropped on attackers（中古时期工事）堞口。
1.1
- a projecting structure containing a series of such openings雉堞式建筑。