(1):

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

(2):

(v. t.) To attach or connect, as a consequence, condition, etc.; as, to annex a penalty to a prohibition, or punishment to guilt.

(3):

(v. t.) To join or attach; usually to subjoin; to affix; to append; - followed by to.

(4):

(v. t.) To join or add, as a smaller thing to a greater.

(5):

(v. i.) To join; to be united.