Source : Webster's Revised Unabridged Dictionary (1913)

Gerund \Ger"und\, n. [L. gerundium, fr. gerere to bear, carry,
   perform. See {Gest} a deed, {Jest}.] (Lat. Gram.)
   1. A kind of verbal noun, having only the four oblique cases
      of the singular number, and governing cases like a
      participle.

   2. (AS. Gram.) A verbal noun ending in -e, preceded by to and
      usually denoting purpose or end; -- called also the
      {dative infinitive}; as, ``Ic h[ae]bbe mete t[^o] etanne''
      (I have meat to eat.) In Modern English the name has been
      applied to verbal or participal nouns in -ing denoting a
      transitive action; e. g., by throwing a stone.

Source : WordNet®

gerund
     n : a noun formed from a verb (such as the `-ing' form of an
         English verb when used as a noun)