Source : Webster's Revised Unabridged Dictionary (1913)

Tunic \Tu"nic\, n. [L. tunica: cf. F. tunique.]
   1. (Rom. Antiq.) An under-garment worn by the ancient Romans
      of both sexes. It was made with or without sleeves,
      reached to or below the knees, and was confined at the
      waist by a girdle.

   2. Any similar garment worm by ancient or Oriental peoples;
      also, a common name for various styles of loose-fitting
      under-garments and over-garments worn in modern times by
      Europeans and others.

   3. (R. C. Ch.) Same as {Tunicle}.

   4. (Anat.) A membrane, or layer of tissue, especially when
      enveloping an organ or part, as the eye.

   5. (Bot.) A natural covering; an integument; as, the tunic of
      a seed.

   6. (Zo["o]l.) See {Mantle}, n., 3
      (a) .

Source : WordNet®

tunic
     n 1: an enveloping or covering membrane or layer of body tissue
          [syn: {tunica}, {adventitia}]
     2: any of a variety of loose fitting cloaks extending to the
        hips or knees