annexe Definition

annexe
annex
noun

1. An additional room, building, area, etc that provides supplementary space.
2. Anything that has been added to something else, especially an extra clause, appendix, etc in a document.

Thesaurus: addition, attachment, adjunct, supplement, addendum, appendix.

Etymology: 19c in sense 1, which takes its spelling directly from French and which subsequently influenced the other sense; 17c in sense 2: French, meaning ‘something joined'.