donjon

American  

[duhn-juhn, don-] / ˈdʌn dʒən, ˈdɒn- /

noun

1. the inner tower, keep, or stronghold of a castle.

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donjon British  

/ ˈdʌndʒən, ˈdɒn- /

noun

1. Also called: dungeon.  the heavily fortified central tower or keep of a medieval castle

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Etymology

Origin of donjon

Variant of dungeon

Example Sentences

Turning to Google, I learned that the English word dungeon emerged several centuries ago from the French donjon, which in turn is thought to have descended from dominio, which is Latin for lord or master.

From Slate • Sep. 25, 2017

However, both donjon and dungeon originally referred to and still refer to, secondarily, a castle keep.

From Slate • Sep. 25, 2017

Oldest part of the grim little hamlet was a "broch tower": a crude donjon keep.

From Time Magazine Archive

Montargis Castle, also built about this time, had a central donjon and a large open enclosure, within which the whole garrison could move freely, to reinforce quickly any threatened point.

From Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 6 "Foraminifera" to "Fox, Edward" by Various

The Rocca or castle is a donjon tower occupying the site of the original fortress of Este.

From The Browning Cyclop?dia A Guide to the Study of the Works of Robert Browning by Berdoe, Edward