Source : Webster's Revised Unabridged Dictionary (1913)

Narrowness \Nar"row*ness\, n. [AS. nearunes.]
   The condition or quality of being narrow.

Source : WordNet®

narrowness
     n 1: the property of being narrow; having little width [ant: {wideness}]
     2: an inclination to criticize opposing opinions or shocking
        behavior [syn: {narrow-mindedness}] [ant: {broad-mindedness}]