Source : Webster's Revised Unabridged Dictionary (1913)

Imagination \Im*ag`i*na"tion\, n. [OE. imaginacionum, F.
   imagination, fr. L. imaginatio. See {Imagine}.]
   1. The imagine-making power of the mind; the power to create
      or reproduce ideally an object of sense previously
      perceived; the power to call up mental imagines.

            Our simple apprehension of corporeal objects, if
            present, is sense; if absent, is imagination.
                                                  --Glanvill.

            Imagination is of three kinds: joined with belief of
            that which is to come; joined with memory of that
            which is past; and of things present, or as if they
            were present.                         --Bacon.

   2. The representative power; the power to reconstruct or
      recombine the materials furnished by direct apprehension;
      the complex faculty usually termed the plastic or creative
      power; the fancy.

            The imagination of common language -- the productive
            imagination of philosophers -- is nothing but the
            representative process plus the process to which I
            would give the name of the ``comparative.'' --Sir W.
                                                  Hamilton.

            The power of the mind to decompose its conceptions,
            and to recombine the elements of them at its
            pleasure, is called its faculty of imagination. --I.
                                                  Taylor.

            The business of conception is to present us with an
            exact transcript of what we have felt or perceived.
            But we have moreover a power of modifying our
            conceptions, by combining the parts of different
            ones together, so as to form new wholes of our
            creation. I shall employ the word imagination to
            express this power.                   --Stewart.

   3. The power to recombine the materials furnished by
      experience or memory, for the accomplishment of an
      elevated purpose; the power of conceiving and expressing
      the ideal.

            The lunatic, the lover, and the poet Are of
            imagination all compact . . . The poet's eye, in a
            fine frenzy rolling, Doth glance from heaven to
            earth, from earth to heaven, And as imagination
            bodies forth The forms of things unknown, the poet's
            pen Turns them to shapes, and gives to airy nothing
            A local habitation and a name.        --Shak.

   4. A mental image formed by the action of the imagination as
      a faculty; a conception; a notion. --Shak.

   Syn: Conception; idea; conceit; fancy; device; origination;
        invention; scheme; design; purpose; contrivance.

   Usage: {Imagination}, {Fancy}. These words have, to a great
          extent, been interchanged by our best writers, and
          considered as strictly synonymous. A distinction,
          however, is now made between them which more fully
          exhibits their nature. Properly speaking, they are
          different exercises of the same general power -- the
          plastic or creative faculty. Imagination consists in
          taking parts of our conceptions and combining them
          into new forms and images more select, more striking,
          more delightful, more terrible, etc., than those of
          ordinary nature. It is the higher exercise of the two.
          It creates by laws more closely connected with the
          reason; it has strong emotion as its actuating and
          formative cause; it aims at results of a definite and
          weighty character. Milton's fiery lake, the debates of
          his Pandemonium, the exquisite scenes of his Paradise,
          are all products of the imagination. Fancy moves on a
          lighter wing; it is governed by laws of association
          which are more remote, and sometimes arbitrary or
          capricious. Hence the term fanciful, which exhibits
          fancy in its wilder flights. It has for its actuating
          spirit feelings of a lively, gay, and versatile
          character; it seeks to please by unexpected
          combinations of thought, startling contrasts, flashes
          of brilliant imagery, etc. Pope's Rape of the Lock is
          an exhibition of fancy which has scarcely its equal in
          the literature of any country. -- ``This, for
          instance, Wordsworth did in respect of the words
          `imagination' and `fancy.' Before he wrote, it was, I
          suppose, obscurely felt by most that in `imagination'
          there was more of the earnest, in `fancy' of the play
          of the spirit; that the first was a loftier faculty
          and gift than the second; yet for all this words were
          continually, and not without loss, confounded. He
          first, in the preface to his Lyrical Ballads, rendered
          it henceforth impossible that any one, who had read
          and mastered what he has written on the two words,
          should remain unconscious any longer of the important
          difference between them.'' --Trench.

                The same power, which we should call fancy if
                employed on a production of a light nature,
                would be dignified with the title of imagination
                if shown on a grander scale.      --C. J. Smith.

Source : WordNet®

imagination
     n 1: the formation of a mental image of something that is not
          perceived as real and is not present to the senses;
          "popular imagination created a world of demons";
          "imagination reveals what the world could be" [syn: {imaginativeness},
           {vision}]
     2: the ability to form mental images of things or events; "he
        could still hear her in his imagination" [syn: {imaging},
        {imagery}, {mental imagery}]
     3: the ability to deal resourcefully with unusual problems; "a
        man of resource" [syn: {resource}, {resourcefulness}]