1. A series of squared notches or indentations cut into the top of a fortified wall or battlement, with the raised parts called merlons and the open parts called crenels.
Usage: Also spelled 'crenelation' or 'crenellation'; Architectural term

1. To furnish (a wall or fortification) with crenels; to provide with a battlement.
Usage: Present participle of 'crenelle'; Architectural/historical term

Examples

• The castle's crenelling provided defenders with protected positions from which to shoot arrows.
• Medieval architects designed crenelling to allow soldiers to fire weapons while remaining sheltered.
• The fortress was crenelling its walls to improve defensive capabilities.
• The distinctive crenelling along the tower's top made it a recognizable landmark.
• They are crenelling the restored wall to match the original medieval design.
• The crenelling pattern on the battlement was typical of 12th-century fortifications.