Source : Webster's Revised Unabridged Dictionary (1913)

Apposition \Ap`po*si"tion\, n. [L. appositio, fr. apponere: cf.
   F. apposition. See {Apposite}.]
   1. The act of adding; application; accretion.

            It grows . . . by the apposition of new matter.
                                                  --Arbuthnot.

   2. The putting of things in juxtaposition, or side by side;
      also, the condition of being so placed.

   3. (Gram.) The state of two nouns or pronouns, put in the
      same case, without a connecting word between them; as, I
      admire Cicero, the orator. Here, the second noun explains
      or characterizes the first.

   {Growth by apposition} (Physiol.), a mode of growth
      characteristic of non vascular tissues, in which nutritive
      matter from the blood is transformed on the surface of an
      organ into solid unorganized substance.

Source : WordNet®

apposition
     n 1: a grammatical relation between a word and a noun phrase that
          follows; "`Rudolph the red-nosed reindeer' is an example
          of apposition"
     2: (biology) growth in the thickness of a cell wall by the
        deposit of successive layers of material
     3: the act of positioning close together (or side by side); "it
        is the result of the juxtaposition of contrasting colors"
        [syn: {juxtaposition}, {collocation}]