Source : Webster's Revised Unabridged Dictionary (1913)

Proper \Prop"er\, a. [OE. propre, F. propre, fr. L. proprius.
   Cf. {Appropriate}.]
   1. Belonging to one; one's own; individual. ``His proper
      good'' [i. e., his own possessions]. --Chaucer. ``My
      proper son.'' --Shak.

            Now learn the difference, at your proper cost,
            Betwixt true valor and an empty boast. --Dryden.

   2. Belonging to the natural or essential constitution;
      peculiar; not common; particular; as, every animal has his
      proper instincts and appetites.

            Those high and peculiar attributes . . . which
            constitute our proper humanity.       --Coleridge.

   3. Befitting one's nature, qualities, etc.; suitable in all
      respect; appropriate; right; fit; decent; as, water is the
      proper element for fish; a proper dress.

            The proper study of mankind is man.   --Pope.

            In Athens all was pleasure, mirth, and play, All
            proper to the spring, and sprightly May. --Dryden.

   4. Becoming in appearance; well formed; handsome. [Archaic]
      ``Thou art a proper man.'' --Chaucer.

            Moses . . . was hid three months of his parents,
            because they saw he was a proper child. --Heb. xi.
                                                  23.

   5. Pertaining to one of a species, but not common to the
      whole; not appellative; -- opposed to {common}; as, a
      proper name; Dublin is the proper name of a city.

   6. Rightly so called; strictly considered; as, Greece proper;
      the garden proper.

   7. (Her.) Represented in its natural color; -- said of any
      object used as a charge.

   {In proper}, individually; privately. [Obs.] --Jer. Taylor.
      

   {Proper flower} or {corolla} (Bot.), one of the single
      florets, or corollets, in an aggregate or compound flower.
      

   {Proper fraction} (Arith.) a fraction in which the numerator
      is less than the denominator.

   {Proper nectary} (Bot.), a nectary separate from the petals
      and other parts of the flower. -- {Proper noun} (Gram.), a
      name belonging to an individual, by which it is
      distinguished from others of the same class; -- opposed to
      {common noun}; as, John, Boston, America.

   {Proper perianth} or {involucre} (Bot.), that which incloses
      only a single flower.

   {Proper receptacle} (Bot.), a receptacle which supports only
      a single flower or fructification.

Fraction \Frac"tion\, n. [F. fraction, L. fractio a breaking,
   fr. frangere, fractum, to break. See {Break}.]
   1. The act of breaking, or state of being broken, especially
      by violence. [Obs.]

            Neither can the natural body of Christ be subject to
            any fraction or breaking up.          --Foxe.

   2. A portion; a fragment.

            Some niggard fractions of an hour.    --Tennyson.

   3. (Arith. or Alg.) One or more aliquot parts of a unit or
      whole number; an expression for a definite portion of a
      unit or magnitude.

   {Common, or Vulgar}, {fraction}, a fraction in which the
      number of equal parts into which the integer is supposed
      to be divided is indicated by figures or letters, called
      the denominator, written below a line, over which is the
      numerator, indicating the number of these parts included
      in the fraction; as 1/2, one half, 2/5, two fifths.

   {Complex fraction}, a fraction having a fraction or mixed
      number in the numerator or denominator, or in both.
      --Davies & Peck.

   {Compound fraction}, a fraction of a fraction; two or more
      fractions connected by of.

   {Continued fraction}, {Decimal fraction}, {Partial fraction},
      etc. See under {Continued}, {Decimal}, {Partial}, etc.

   {Improper fraction}, a fraction in which the numerator is
      greater than the denominator.

   {Proper fraction}, a fraction in which the numerator is less
      than the denominator.

Source : WordNet®

proper fraction
     n : a fraction with a numerator smaller than the denominator