What does annex mean?
The definition of annex
An*nex”, v. t.
[imp. & p. p. Annexed; p. pr. & vb. n. Annexing.]
Etym: [F. annexer, fr. L. annexus, p. p. of annectere to tie or bind to; ad + nectere to tie, to fasten together, akin to Skr. nah to bind.]

1 To join or attach; usually to subjoin; to affix; to append; — followed by to. “He annexed a codicil to a will.” Johnson.
2 To join or add, as a smaller thing to a greater. He annexed a province to his kingdom. Johnson.
3 To attach or connect, as a consequence, condition, etc.; as, to annex a penalty to a prohibition, or punishment to guilt.

Synonyms
— To add; append; affix; unite; coalesce. See Add.

An*nex”, v. i.
To join; to be united. Tooke.
An*nex”, n.
Etym: [F. annexe, L. annexus, neut. annexum, p. p. of annectere.]

Something annexed or appended; as, an additional stipulation to a writing, a subsidiary building to a main building; a wing.