Source : Webster's Revised Unabridged Dictionary (1913)

Tailing \Tail"ing\, n.
   1. (Arch.) The part of a projecting stone or brick inserted
      in a wall. --Gwilt.

   2. (Surg.) Same as {Tail}, n., 8
      (a) .

   3. Sexual intercourse. [Obs.] --Chaucer.

   4. pl. The lighter parts of grain separated from the seed
      threshing and winnowing; chaff.

   5. pl. (Mining) The refuse part of stamped ore, thrown behind
      the tail of the buddle or washing apparatus. It is dressed
      over again to secure whatever metal may exist in it.
      Called also {tails}. --Pryce.

Source : WordNet®

tails
     n : formalwear consisting of full evening dress for men [syn: {dress
         suit}, {full dress}, {tailcoat}, {tail coat}, {white tie},
          {white tie and tails}]