The Collaborative International Dictionary of English v.0.48:

Single \Sin"gle\, a. [L. singulus, a dim. from the root in
   simplex simple; cf. OE. & OF. sengle, fr. L. singulus. See
   Simple, and cf. Singular.]
   1. One only, as distinguished from more than one; consisting
      of one alone; individual; separate; as, a single star.
      [1913 Webster]

            No single man is born with a right of controlling
            the opinions of all the rest.         --Pope.
      [1913 Webster]

   2. Alone; having no companion.
      [1913 Webster]

            Who single hast maintained,
            Against revolted multitudes, the cause
            Of truth.                             --Milton.
      [1913 Webster]

   3. Hence, unmarried; as, a single man or woman.
      [1913 Webster]

            Grows, lives, and dies in single blessedness.
                                                  --Shak.
      [1913 Webster]

            Single chose to live, and shunned to wed. --Dryden.
      [1913 Webster]

   4. Not doubled, twisted together, or combined with others;
      as, a single thread; a single strand of a rope.
      [1913 Webster]

   5. Performed by one person, or one on each side; as, a single
      combat.
      [1913 Webster]

            These shifts refuted, answer thy appellant, . . .
            Who now defles thee thrice ti single fight.
                                                  --Milton.
      [1913 Webster]

   6. Uncompounded; pure; unmixed.
      [1913 Webster]

            Simple ideas are opposed to complex, and single to
            compound.                             --I. Watts.
      [1913 Webster]

   7. Not deceitful or artful; honest; sincere.
      [1913 Webster]

            I speak it with a single heart.       --Shak.
      [1913 Webster]

   8. Simple; not wise; weak; silly. [Obs.]
      [1913 Webster]

            He utters such single matter in so infantly a voice.
                                                  --Beau. & Fl.
      [1913 Webster]

   Single ale, Single beer, or Single drink, small ale,
      etc., as contrasted with double ale, etc., which is
      stronger. [Obs.] --Nares.

   Single bill (Law), a written engagement, generally under
      seal, for the payment of money, without a penalty.
      --Burril.

   Single court (Lawn Tennis), a court laid out for only two
      players.

   Single-cut file. See the Note under 4th File.

   Single entry. See under Bookkeeping.

   Single file. See under 1st File.

   Single flower (Bot.), a flower with but one set of petals,
      as a wild rose.

   Single knot. See Illust. under Knot.

   Single whip (Naut.), a single rope running through a fixed
      block.
      [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.
             [1913 Webster]

   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.
          [1913 Webster]

                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.]
      [1913 Webster]

            Let me resume the file of my narration. --Sir H.
                                                  Wotton.
      [1913 Webster]

   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):

single file
    n 1: a line of persons or things ranged one behind the other
         [syn: file, single file, Indian file]

Moby Thesaurus II by Grady Ward, 1.0:

55 Moby Thesaurus words for "single file":
   Indian file, array, articulation, bank, buzz, catena, catenation,
   chain, chain reaction, chaining, concatenation, connection,
   consecution, continuum, course, cycle, descent, drone,
   endless belt, endless round, file, filiation, gamut, gradation,
   hum, line, lineage, monotone, nexus, pendulum, periodicity, plenum,
   powder train, progression, queue, range, rank, recurrence,
   reticulation, rotation, round, routine, row, run, scale, sequence,
   series, spectrum, string, succession, swath, thread, tier, train,
   windrow