All 8 Uses of

rampart
in
Harry Potter (#6) and the Half-Blood Prince

Dumbledore had already crossed the crenellated ramparts and was dismounting; Harry landed next to him seconds later and looked around.†
Chpt 27 *

He could not understand how it had happened — Expelliarmus was not a Freezing Charm — Then, by the light of the Mark, he saw Dumbledore's wand flying in an arc over the edge of the ramparts and under-stood ...Dumbledore had wordlessly immobilised Harry, and the second he had taken to perform the spell had cost him the chance of defending himself.†
Chpt 27

Standing against the ramparts, very white in the face, Dumbledore still showed no sign of panic or distress.†
Chpt 27

And you resorted to crude and badly judged meas-ures such as sending me a cursed necklace that was bound to reach the wrong hands ...poisoning mead there was only the slightest chance I might drink ...' 'Yeah, well, you still didn't realise who was behind that stuff, did you?' sneered Malfoy, as Dumbledore slid a little down the ramparts, the strength in his legs apparently fading, and Harry struggled fruitlessly, mutely, against the enchantment binding him.†
Chpt 27

He looked terrified as he stared into Dumbledore's face, which was even paler, and rather lower than usual, as he had slid so far down the rampart wall.†
Chpt 27

'I said no!' shouted the brutal-faced man; there was a flash of light and the werewolf was blasted out of the way; he hit the ramparts and staggered, looking furious.†
Chpt 27

Harry's heart was hammering so hard it seemed impossible that nobody could hear him standing there, imprisoned by Dumbledore's spell —if he could only move, he could aim a curse from under the Cloak — 'Draco, do it, or stand aside so one of us —' screeched the woman, but at that precise moment the door to the ramparts burst open once more and there stood Snape, his wand clutched in his hand as his black eyes swept the scene, from Dumbledore slumped against the wall, to the four Death Eaters, including the enraged werewolf, and Malfoy.†
Chpt 27

Definition:

a defensive wall or barrier -- built for military defense