Source : Webster's Revised Unabridged Dictionary (1913)

   Note: If we examine a common flower, such for instance as a
         geranium, we shall find that it consists of: First, an
         outer envelope or calyx, sometimes tubular, sometimes
         consisting of separate leaves called sepals; secondly,
         an inner envelope or corolla, which is generally more
         or less colored, and which, like the calyx, is
         sometimes tubular, sometimes composed of separate
         leaves called petals; thirdly, one or more stamens,
         consisting of a stalk or filament and a head or anther,
         in which the pollen is produced; and fourthly, a
         pistil, which is situated in the center of the flower,
         and consists generally of three principal parts; one or
         more compartments at the base, each containing one or
         more seeds; the stalk or style; and the stigma, which
         in many familiar instances forms a small head, at the
         top of the style or ovary, and to which the pollen must
         find its way in order to fertilize the flower. --Sir J.
         Lubbock.

   3. The fairest, freshest, and choicest part of anything; as,
      the flower of an army, or of a family; the state or time
      of freshness and bloom; as, the flower of life, that is,
      youth.

            The choice and flower of all things profitable the
            Psalms do more briefly contain.       --Hooker.

            The flower of the chivalry of all Spain. --Southey.

            A simple maiden in her flower Is worth a hundred
            coats of arms.                        --Tennyson.

   4. Grain pulverized; meal; flour. [Obs.]

            The flowers of grains, mixed with water, will make a
            sort of glue.                         --Arbuthnot.

   5. pl. (Old. Chem.) A substance in the form of a powder,
      especially when condensed from sublimation; as, the
      flowers of sulphur.

   6. A figure of speech; an ornament of style.

   7. pl. (Print.) Ornamental type used chiefly for borders
      around pages, cards, etc. --W. Savage.

   8. pl. Menstrual discharges. --Lev. xv. 24.

   {Animal flower} (Zo["o]l.) See under {Animal}.

   {Cut flowers}, flowers cut from the stalk, as for making a
      bouquet.

   {Flower bed}, a plat in a garden for the cultivation of
      flowers.

   {Flower beetle} (Zo["o]l.), any beetle which feeds upon
      flowers, esp. any one of numerous small species of the
      genus {Meligethes}, family {Nitidulid[ae]}, some of which
      are injurious to crops.

   {Flower bird} (Zo["o]l.), an Australian bird of the genus
      {Anthornis}, allied to the honey eaters.

   {Flower bud}, an unopened flower.

   {Flower clock}, an assemblage of flowers which open and close
      at different hours of the day, thus indicating the time.
      

   {Flower head} (Bot.), a compound flower in which all the
      florets are sessile on their receptacle, as in the case of
      the daisy.

   {Flower pecker} (Zo["o]l.), one of a family ({Dic[ae]id[ae]})
      of small Indian and Australian birds. They resemble
      humming birds in habits.

   {Flower piece}.
      (a) A table ornament made of cut flowers.
      (b) (Fine Arts) A picture of flowers.

   {Flower stalk} (Bot.), the peduncle of a plant, or the stem
      that supports the flower or fructification.

Source : WordNet®

flower bud
     n : a bud from which only a flower or flowers develop