The Collaborative International Dictionary of English v.0.48:

Imagine \Im*ag"ine\, v. t. [imp. & p. p. Imagined; p. pr. &
   vb. n. Imagining.] [F. imaginer, L. imaginari, p. p.
   imaginatus, fr. imago image. See Image.]
   1. To form in the mind a notion or idea of; to form a mental
      image of; to conceive; to produce by the imagination.
      [1913 Webster]

            In the night, imagining some fear,
            How easy is a bush supposed a bear!   --Shak.
      [1913 Webster]

   2. To contrive in purpose; to scheme; to devise; to compass;
      to purpose. See Compass, v. t., 5.
      [1913 Webster]

            How long will ye imagine mischief against a man?
                                                  --Ps. lxii. 3.
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   3. To represent to one's self; to think; to believe. --Shak.

   Syn: To fancy; conceive; apprehend; think; believe; suppose;
        opine; deem; plan; scheme; devise.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

imagined \imagined\ adj.
   existing in the mind only; not real or actual; as, her
   imagined fame.

   Syn: imaginary, notional.
        [WordNet 1.5]