A building or wing added to or connected with a main building; an addition or supplement to something.
From French 'annexe' (also the source of English 'annex'), from Latin 'annexus' meaning bound to or attached, from 'annectere' (to bind).
Victorian mansions often had multiple annexes for kitchens, servants, and storage—if you understand the layout of a noble's annexes, you can literally see how class divisions were built into architecture.
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