Source : Webster's Revised Unabridged Dictionary (1913)

Arab \Ar"ab\ (?; 277), n. [Prob. ultimately fr. Heb. arabah a
   desert, the name employed, in the Old Testament, to denote
   the valley of the Jordan and Dead Sea. Ar. Arab, Heb. arabi,
   arbi, arbim: cf. F. Arabe, L. Arabs, Gr. ?.]
   One of a swarthy race occupying Arabia, and numerous in
   Syria, Northern Africa, etc.

   {Street Arab}, a homeless vagabond in the streets of a city,
      particularly and outcast boy or girl. --Tylor.

            The ragged outcasts and street Arabs who are
            shivering in damp doorways.           --Lond. Sat.
                                                  Rev.

Source : WordNet®

Arab
     n 1: a member of a Semitic people originally from the Arabian
          peninsula and surrounding territories who speaks Arabic
          and who inhabits much of the Middle East and northern
          Africa [syn: {Arabian}]
     2: a spirited graceful and intelligent riding horse native to
        Arabia [syn: {Arabian}]