Source : Webster's Revised Unabridged Dictionary (1913)

Rank \Rank\, n. [OE. renk, reng, OF. renc, F. rang, fr. OHG.
   hring a circle, a circular row, G. ring. See {Ring}, and cf.
   {Range}, n. & v.]
   1. A row or line; a range; an order; a tier; as, a rank of
      osiers.

            Many a mountain nigh Rising in lofty ranks, and
            loftier still.                        --Byron.

   2. (Mil.) A line of soldiers ranged side by side; -- opposed
      to file. See 1st {File}, 1
      (a) .

                Fierce, fiery warriors fought upon the clouds,
                In ranks and squadrons and right form of war.
                                                  --Shak.

   3. Grade of official standing, as in the army, navy, or
      nobility; as, the rank of general; the rank of admiral.

   4. An aggregate of individuals classed together; a permanent
      social class; an order; a division; as, ranks and orders
      of men; the highest and the lowest ranks of men, or of
      other intelligent beings.

   5. Degree of dignity, eminence, or excellence; position in
      civil or social life; station; degree; grade; as, a writer
      of the first rank; a lawyer of high rank.

            These all are virtues of a meaner rank. --Addison.

   6. Elevated grade or standing; high degree; high social
      position; distinction; eminence; as, a man of rank.

   {Rank and file}.
      (a) (Mil.) The whole body of common soldiers, including
          also corporals. In a more extended sense, it includes
          sergeants also, excepting the noncommissioned staff.



   2. Course of thought; thread of narration. [Obs.]

            Let me resume the file of my narration. --Sir H.
                                                  Wotton.

   {File firing}, the act of firing by file, or each file
      independently of others.

   {File leader}, the soldier at the front of any file, who
      covers and leads those in rear of him.

   {File marching}, the marching of a line two deep, when faced
      to the right or left, so that the front and rear rank
      march side by side. --Brande & C. 

   {Indian file}, or {Single file}, a line of men marching one
      behind another; a single row.

   {On file}, preserved in an orderly collection.

   {Rank and file}.
      (a) The body of soldiers constituing the mass of an army,
          including corporals and privates. --Wilhelm.
      (b) Those who constitute the bulk or working members of a
          party, society, etc., in distinction from the leaders.

Source : WordNet®

rank and file
     n 1: the ordinary members of an organization (such as the
          enlisted soldiers of an army); "the strike was supported
          by the union rank and file"; "he rose from the ranks to
          become a colonel" [syn: {rank}]
     2: people who constitute the main body of any group