The Collaborative International Dictionary of English v.0.48:

Prismatic \Pris*mat"ic\, Prismatical \Pris*mat"ic*al\, a. [Cf.
   F. prismatique.]
   1. Resembling, or pertaining to, a prism; as, a prismatic
      form or cleavage.
      [1913 Webster]

   2. Separated or distributed by a prism; formed by a prism;
      as, prismatic colors.
      [1913 Webster]

   3. (Crystallog.) Same as Orthorhombic.
      [1913 Webster]

   Prismatic borax (Chem.), borax crystallized in the form of
      oblique prisms, with ten molecules of water; --
      distinguished from octahedral borax.

   Prismatic colors (Opt.), the seven colors into which light
      is resolved when passed through a prism; primary colors.
      See Primary colors, under Color.

   Prismatic compass (Surv.), a compass having a prism for
      viewing a distant object and the compass card at the same
      time.

   Prismatic spectrum (Opt.), the spectrum produced by the
      passage of light through a prism.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

colorful \colorful\ adj.
   1. having striking color. Opposite of colorless.

   Note: [Narrower terms: changeable, chatoyant, iridescent,
         shot; deep, rich; flaming; fluorescent, glowing;
         prismatic; psychedelic; red, ruddy, flushed,
         empurpled]

   Syn: colourful.
        [WordNet 1.5]

   2. striking in variety and interest. Opposite of colorless
      or dull. [Narrower terms: brave, fine, gay, glorious;
      flamboyant, resplendent, unrestrained; flashy, gaudy,
      jazzy, showy, snazzy, sporty; picturesque]
      [WordNet 1.5]

   3. having color or a certain color; not black, white or grey;
      as, colored crepe paper. Opposite of colorless and
      monochrome.

   Note: [Narrower terms: tinted; touched, tinged; amber,
         brownish-yellow, yellow-brown; amethyst; auburn,
         reddish-brown; aureate, gilded, gilt, gold, golden;
         azure, cerulean, sky-blue, bright blue; bicolor,
         bicolour, bicolored, bicoloured, bichrome; blue,
         bluish, light-blue, dark-blue; blushful,
         blush-colored, rosy; bottle-green; bronze, bronzy;
         brown, brownish, dark-brown; buff; canary,
         canary-yellow; caramel, caramel brown; carnation;
         chartreuse; chestnut; dun; earth-colored,
         earthlike; fuscous; green, greenish, light-green,
         dark-green; jade, jade-green; khaki; lavender,
         lilac; mauve; moss green, mosstone; motley,
         multicolor, culticolour, multicolored, multicoloured,
         painted, particolored, particoloured, piebald, pied,
         varicolored, varicoloured; mousy, mouse-colored;
         ocher, ochre; olive-brown; olive-drab; olive;
         orange, orangish; peacock-blue; pink, pinkish;
         purple, violet, purplish; red, blood-red, carmine,
         cerise, cherry, cherry-red, crimson, ruby, ruby-red,
         scarlet; red, reddish; rose, roseate; rose-red;
         rust, rusty, rust-colored; snuff, snuff-brown,
         snuff-color, snuff-colour, snuff-colored,
         snuff-coloured, mummy-brown, chukker-brown; sorrel,
         brownish-orange; stone, stone-gray; straw-color,
         straw-colored, straw-coloured; tan; tangerine;
         tawny; ultramarine; umber; vermilion,
         vermillion, cinibar, Chinese-red; yellow, yellowish;
         yellow-green; avocado; bay; beige; blae
         bluish-black or gray-blue); coral; creamy; cress
         green, cresson, watercress; hazel; honey,
         honey-colored; hued(postnominal); magenta;
         maroon; pea-green; russet; sage, sage-green;
         sea-green] [Also See: chromatic, colored, dark,
         light.]

   Syn: colored, coloured, in color(predicate).
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

prismatic
    adj 1: of or relating to or resembling or constituting a prism;
           "prismatic form"
    2: exhibiting spectral colors formed by refraction of light
       through a prism; "prismatic light"

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "prismatic":
   bicolor, bicolored, chromatic, cold, colorful, colorific, coloring,
   colory, cool, crazy, daedal, dichromatic, divers-colored, glowing,
   harlequin, harmonious, kaleidoscopic, many-colored, matching,
   medley, monochromatic, monochrome, monochromic, motley,
   multiangular, multicolor, multicolored, multicolorous,
   multilateral, parti-color, parti-colored, pigmentary,
   polychromatic, polychrome, polychromic, polygonal, polyhedral,
   prismal, prismoid, pyramidal, pyramidic, rainbow, shot,
   shot through, spectral, thunder and lightning, tinctorial, tingent,
   toning, trichromatic, trichromic, tricolor, tricolored, two-tone,
   varicolored, variegated, versicolor, versicolored, warm