Definitions:

1. A defensive structure that projects outwards from the top of a wall or tower, that typically includes a series of openings in the floor, allowing defenders to attack enemies directly beneath the fortification. NOUN
   • During a siege, the defenders used the machicolations to pour hot oil on the attacking soldiers.
2. A floor opening between the supporting corbels of a battlement, through which stones, hot oil, heated sand, or other harmful substances could be dropped on attackers at the base of a defensive wall. NOUN
   • The main gate was heavily fortified with machicolations to deter any direct assault.
3. Architectural feature commonly found in medieval fortifications, such as castles and city walls. NOUN
   • The castle's battlements were equipped with machicolations to provide additional defense against invaiders.

Synonyms:

• battlement
• breastwork
• loophole
• parapet