The Collaborative International Dictionary of English v.0.48:

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.
      [1913 Webster]

            Many a mountain nigh
            Rising in lofty ranks, and loftier still. --Byron.
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   2. (Mil.) A line of soldiers ranged side by side; -- opposed
      to file. See 1st File, 1
      (a) .
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                Fierce, fiery warriors fought upon the clouds,
                In ranks and squadrons and right form of war.
                                                  --Shak.
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   3. Grade of official standing, as in the army, navy, or
      nobility; as, the rank of general; the rank of admiral.
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   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.
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   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.
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            These all are virtues of a meaner rank. --Addison.
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   6. Elevated grade or standing; high degree; high social
      position; distinction; eminence; as, a man of rank.
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   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.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

File \File\ (f[imac]l), n. [F. file row (cf. Pr., Sp., Pg., &
   It. fila), LL. fila, fr. L. filum a thread. Cf. Enfilade,
   Filament, Fillet.]
   1. An orderly succession; a line; a row; as:
      (a)
      (Mil.) A row of soldiers ranged one behind another; -- in
             contradistinction to rank, which designates a row
             of soldiers standing abreast; a number consisting
             the depth of a body of troops, which, in the
             ordinary modern formation, consists of two men, the
             battalion standing two deep, or in two ranks.
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   Note: The number of files in a company describes its width,
         as the number of ranks does its depth; thus, 100 men in
         "fours deep" would be spoken of as 25 files in 4 ranks.
         --Farrow.
      (b) An orderly collection of papers, arranged in sequence
          or classified for preservation and reference; as,
          files of letters or of newspapers; this mail brings
          English files to the 15th instant.
      (c) The line, wire, or other contrivance, by which papers
          are put and kept in order.
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                It is upon a file with the duke's other letters.
                                                  --Shak.
      (d) A roll or list. "A file of all the gentry." --Shak.

   2. Course of thought; thread of narration. [Obs.]
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            Let me resume the file of my narration. --Sir H.
                                                  Wotton.
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   3. (computers) a collection of data on a digital recording
      medium treated as a unit for the purpose of recording,
      reading, storage, or indexing; -- such a file is typically
      accessible by computer programs by the use of a file name.
      The data may be of any type codable digitally, such as
      simple ASCII-coded text, complex binary-coded data, or an
      executable program, or may be itself a collection of other
      files.
      [PJC]

   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 people marching
      one behind another; a single row. Also used adverbially;
      as, to march Indian file.

   On file, preserved in an orderly collection; recorded in
      some database.

   Rank and file.
      (a) The body of soldiers constituting 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.
          [1913 Webster]

WordNet (r) 3.0 (2006):

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 and file, rank]
    2: people who constitute the main body of any group

Moby Thesaurus II by Grady Ward, 1.0:

64 Moby Thesaurus words for "rank and file":
   armed force, armed service, army, array, bourgeoisie,
   career soldiers, common people, common run, common sort, commonage,
   commonality, commonalty, commoners, commons, fighting machine,
   forces, ground forces, ground troops, host, laborers, legions,
   linendrapers, lower classes, lower middle class, lower orders,
   lumpen proletariat, majority, members, middle class, middle orders,
   military establishment, occupation force, ordinary people,
   paratroops, peasantry, people, plain folks, plain people,
   plebeians, plebes, populace, proletariat, ranks, regular army,
   regulars, shopkeepers, ski troops, small tradesmen, soldiery,
   standing army, storm troops, the line, the lower cut, the military,
   the other half, the third estate, third estate, toilers,
   toiling class, troops, upper middle class, vulgus, working class,
   working people