1. [n]  an addition that extends a main building
2. [v]  attach to
3. [v]  take by conquest; as of territory
4. [v]  take illegally, as of territory

ANNEX is a 5 letter word that starts with A.

1. \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.
   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.
   Syn: To add; append; affix; unite; coalesce. See {Add}.
   

2. \An*nex"\, v. i.
   To join; to be united. --Tooke.
   

3. \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.