The Collaborative International Dictionary of English v.0.48:

Fertile \Fer"tile\ (? or ?; 277), a. [L. fertilis, fr. ferre to
   bear, produce: cf. F. fertile. See Bear to support.]
   1. Producing fruit or vegetation in abundance; fruitful; able
      to produce abundantly; prolific; fecund; productive; rich;
      inventive; as, fertile land or fields; a fertile mind or
      imagination.
      [1913 Webster]

            Though he in a fertile climate dwell. --Shak.
      [1913 Webster]

   2. (Bot.)
      (a) Capable of producing fruit; fruit-bearing; as, fertile
          flowers.
      (b) Containing pollen; -- said of anthers.
          [1913 Webster]

   3. produced in abundance; plenteous; ample.
      [1913 Webster]

            Henceforth, my early care . . .
            Shall tend thee, and the fertile burden ease
            Of thy full branches.                 --Milton.

   Syn: Fertile, Fruitful.

   Usage: Fertile implies the inherent power of production;
          fruitful, the act. The prairies of the West are
          fertile by nature, and are turned by cultivation into
          fruitful fields. The same distinction prevails when
          these words are used figuratively. A man of fertile
          genius has by nature great readiness of invention; one
          whose mind is fruitful has resources of thought and a
          readiness of application which enable him to think and
          act effectively.
          [1913 Webster]

WordNet (r) 3.0 (2006):

fertile
    adj 1: capable of reproducing [ant: infertile, sterile,
           unfertile]
    2: intellectually productive; "a prolific writer"; "a fecund
       imagination" [syn: fecund, fertile, prolific]
    3: bearing in abundance especially offspring; "flying foxes are
       extremely prolific"; "a prolific pear tree" [syn: prolific,
       fertile]
    4: marked by great fruitfulness; "fertile farmland"; "a fat
       land"; "a productive vineyard"; "rich soil" [syn: fat,
       fertile, productive, rich]