Source : Webster's Revised Unabridged Dictionary (1913)

Oblong \Ob"long\, n.
   A rectangular figure longer than it is broad; hence, any
   figure longer than it is broad.

         The best figure of a garden I esteem an oblong upon a
         descent.                                 --Sir W.
                                                  Temple.

Oblong \Ob"long\, a. [L. oblongus; ob (see {Ob-}) + longus long:
   cf. F. oblong.]
   Having greater length than breadth, esp. when rectangular.

Source : WordNet®

oblong
     adj 1: of a leaf shape; having a somewhat elongated form with
            approximately parallel sides
     2: deviating from a square or circle or sphere by being
        elongated in one direction

oblong
     n : a plane figure that deviates from a square or circle due to
         elongation