Source : Webster's Revised Unabridged Dictionary (1913)

Ensign \En"sign\, n. [L. enseigne, L. insignia, pl. of insigne a
   distinctive mark, badge, flag; in + signum mark, sign. See
   {Sign}, and cf. {Insignia}, 3d {Ancient}.]
   1. A flag; a banner; a standard; esp., the national flag, or
      a banner indicating nationality, carried by a ship or a
      body of soldiers; -- as distinguished from flags
      indicating divisions of the army, rank of naval officers,
      or private signals, and the like.

            Hang up your ensigns, let your drums be still.
                                                  --Shak.

   2. A signal displayed like a standard, to give notice.

            He will lift an ensign to the nations from far.
                                                  --Is. v. 26.

   3. Sign; badge of office, rank, or power; symbol.

            The ensigns of our power about we bear. --Waller.

   4.
      (a) Formerly, a commissioned officer of the army who
          carried the ensign or flag of a company or regiment.
      (b) A commissioned officer of the lowest grade in the
          navy, corresponding to the grade of second lieutenant
          in the army. --Ham. Nav. Encyc.

   Note: In the British army the rank of ensign was abolished in
         1871. In the United States army the rank is not
         recognized; the regimental flags being carried by a
         sergeant called the color sergeant.

   {Ensign bearer}, one who carries a flag; an ensign.

Ensign \En"sign\, v. t.
   1. To designate as by an ensign. [Obs.]

            Henry but joined the roses that ensigned Particular
            families.                             --B. Jonson.

   2. To distinguish by a mark or ornament; esp. (Her.), by a
      crown; thus, any charge which has a crown immediately
      above or upon it, is said to be ensigned.

Source : WordNet®

ensign
     n 1: a person who holds a commissioned rank in the United States
          Navy or the United States Coast Guard; below lieutenant
          junior grade
     2: an emblem flown as a symbol of nationality [syn: {national
        flag}]
     3: colors flown by a ship to show its nationality