The Collaborative International Dictionary of English v.0.48:

Annex \An*nex"\, v. t. [imp. & p. p. Annexed; p. pr. & vb. n.
   Annexing.] [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.
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   2. To join or add, as a smaller thing to a greater.
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            He annexed a province to his kingdom. --Johnson.
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   3. To attach or connect, as a consequence, condition, etc.;
      as, to annex a penalty to a prohibition, or punishment to
      guilt.
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   Syn: To add; append; affix; unite; coalesce. See Add.
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The Collaborative International Dictionary of English v.0.48:

Annex \An*nex"\, v. i.
   To join; to be united. --Tooke.
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The Collaborative International Dictionary of English v.0.48:

Annex \An*nex"\, n. [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.
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WordNet (r) 3.0 (2006):

annex
    n 1: an addition that extends a main building [syn: annex,
         annexe, extension, wing]
    v 1: take (territory) as if by conquest; "Hitler annexed
         Lithuania"
    2: attach to