estre
The indoor layout or plan of a castle.
archaic, obsolete
"And tomorrow, Cor," he added, "shalt come over all the castle with me and see the estres and mark all its strength and weakness: for it will be thine to guard when I'm gone."
Where it comes from
From Old French estre (“state, plan”). Cognate with some forms of be (including am, is and are).
Adapted from the Wiktionary entry estre (CC BY-SA 4.0).