The Collaborative International Dictionary of English v.0.48:

Figment \Fig"ment\, n. [L. figmentum, fr. fingere to form,
   shape, invent, feign. See Feign.]
   An invention; a fiction; something feigned or imagined.
   [1913 Webster]

         Social figments, feints, and formalism.  --Mrs.
                                                  Browning.
   [1913 Webster]

         It carried rather an appearance of figment and
         invention . . . than of truth and reality. --Woodward.
   [1913 Webster]

WordNet (r) 3.0 (2006):

figment
    n 1: a contrived or fantastic idea; "a figment of the
         imagination"

Moby Thesaurus II by Grady Ward, 1.0:

42 Moby Thesaurus words for "figment":
   apparition, brainchild, bubble, canard, chimera, concoction,
   creation, daydream, delirium, dream, eidolon, extravaganza, fable,
   fabrication, fancy, fantasque, fantasy, fiction, forgery,
   hallucination, idle fancy, illusion, imagery, imagination,
   imagining, insubstantial image, invention, maggot, make-believe,
   myth, nightmare, phantasm, phantom, romance, sick fancy,
   thick-coming fancies, trip, vapor, vision, whim, whimsy,
   wildest dreams