The Collaborative International Dictionary of English v.0.48:

Narrow \Nar"row\ (n[a^]r"r[-o]), a. [Compar. Narrower
   (n[a^]r"r[-o]*[~e]r); superl. Narrowest.] [OE. narwe, naru,
   AS. nearu; akin to OS. naru, naro.]
   1. Of little breadth; not wide or broad; having little
      distance from side to side; as, a narrow board; a narrow
      street; a narrow hem.
      [1913 Webster]

            Hath passed in safety through the narrow seas.
                                                  --Shak.
      [1913 Webster]

   2. Of little extent; very limited; circumscribed.
      [1913 Webster]

            The Jews were but a small nation, and confined to a
            narrow compass in the world.          --Bp. Wilkins.
      [1913 Webster]

   3. Having but a little margin; having barely sufficient
      space, time, or number, etc.; close; near[5]; -- with
      special reference to some peril or misfortune; as, a
      narrow shot; a narrow escape; a narrow miss; a narrow
      majority. --Dryden.
      [1913 Webster]

   4. Limited as to means; straitened; pinching; as, narrow
      circumstances.
      [1913 Webster]

   5. Contracted; of limited scope; illiberal; bigoted; as, a
      narrow mind; narrow views. "A narrow understanding."
      --Macaulay.
      [1913 Webster]

   6. Parsimonious; niggardly; covetous; selfish.
      [1913 Webster]

            A very narrow and stinted charity.    --Smalridge.
      [1913 Webster]

   7. Scrutinizing in detail; close; accurate; exact.
      [1913 Webster]

            But first with narrow search I must walk round
            This garden, and no corner leave unspied. --Milton.
      [1913 Webster]

   8. (Phon.) Formed (as a vowel) by a close position of some
      part of the tongue in relation to the palate; or
      (according to Bell) by a tense condition of the pharynx;
      -- distinguished from wide; as [=e] ([=e]ve) and [=oo]
      (f[=oo]d), etc., from [i^] ([i^]ll) and [oo^] (f[oo^]t),
      etc. See Guide to Pronunciation, [sect]13.
      [1913 Webster]

   Note: Narrow is not unfrequently prefixed to words,
         especially to participles and adjectives, forming
         compounds of obvious signification; as,
         narrow-bordered, narrow-brimmed, narrow-breasted,
         narrow-edged, narrow-faced, narrow-headed,
         narrow-leaved, narrow-pointed, narrow-souled,
         narrow-sphered, etc.
         [1913 Webster]

   Narrow gauge. (Railroad) See Note under Gauge, n., 6.
      [1913 Webster]

WordNet (r) 3.0 (2006):

narrow gauge
    n 1: a railroad track (or its width) narrower than the standard
         56.5 inches

Moby Thesaurus II by Grady Ward, 1.0:

61 Moby Thesaurus words for "narrow gauge":
   angustifoliate, angustirostrate, angustisellate, angustiseptal,
   authoritarian, bigot, bigoted, borne, circumscribed, close,
   close-fitting, closed, confined, constricted, cramp, cramped,
   creedbound, crowded, deaf, deaf to reason, fanatical, hidebound,
   illiberal, incapacious, incommodious, insular, isthmian, isthmic,
   limited, little, little-minded, meager, mean, mean-minded,
   mean-spirited, narrow, narrow-hearted, narrow-minded,
   narrow-souled, narrow-spirited, near, nearsighted, parochial,
   petty, provincial, purblind, restricted, scant, scanty,
   shortsighted, slender, small, small-minded, strait, straitlaced,
   stuffy, tight, uncatholic, uncharitable, ungenerous, unliberal