The Collaborative International Dictionary of English v.0.48:

Palette \Pal"ette\, n. [See Pallet a thin board.]
   [1913 Webster]
   1. (Paint.) A thin, oval or square board, or tablet, with a
      thumb hole at one end for holding it, on which a painter
      lays and mixes his pigments. Hence, any other object,
      usually one with a flat surface, used for the same
      purpose. [Written also pallet.]
      [1913 Webster]

   2. Hence: The complete set of colors used by an artist or
      other person in creating an image, in any medium. The
      meaning of this term has been extended in modern times to
      include the set of colors used in a particular computer
      application, or the complete set of of colors available in
      computer displays or printing techniques.
      [PJC]

   3. Hence: The complete range of resources and techniques used
      in any art, such as music.
      [PJC]

   4. (Anc. Armor) One of the plates covering the points of
      junction at the bend of the shoulders and elbows.
      --Fairholt.
      [1913 Webster]

   5. (Mech.) A breastplate for a breast drill.
      [1913 Webster]

   Palette knife, a knife with a very flexible steel blade and
      no cutting edge, rounded at the end, used by painters to
      mix colors on the grinding slab or palette.

   To set the palette (Paint.), to lay upon it the required
      pigments in a certain order, according to the intended use
      of them in a picture. --Fairholt.
      [1913 Webster]

WordNet (r) 3.0 (2006):

palette
    n 1: the range of colour characteristic of a particular artist
         or painting or school of art [syn: palette, pallet]
    2: board that provides a flat surface on which artists mix
       paints and the range of colors used [syn: palette,
       pallet]
    3: one of the rounded armor plates at the armpits of a suit of
       armor [syn: pallette, palette]

Moby Thesaurus II by Grady Ward, 1.0:

32 Moby Thesaurus words for "palette":
   air brush, art paper, brush, camera lucida, camera obscura, canvas,
   chalk, charcoal, crayon, drawing paper, drawing pencil, drier,
   easel, fixative, ground, lay figure, maulstick, medium, paint,
   paintbrush, palette knife, pastel, pencil, pigments, scratchboard,
   siccative, sketchbook, sketchpad, spatula, spray gun, stump,
   varnish



The Free On-line Dictionary of Computing (30 December 2018):

colour palette
CLUT
colour look-up table
palette

    (colour look-up table, CLUT) A device
   which converts the logical colour numbers stored in each
   pixel of video memory into physical colours, normally
   represented as RGB triplets, that can be displayed on the
   monitor.  The palette is simply a block of fast RAM which
   is addressed by the logical colour and whose output is split
   into the red, green and blue levels which drive the actual
   display (e.g. CRT).

   The number of entries (logical colours) in the palette is the
   total number of colours which can appear on screen
   simultaneously.  The width of each entry determines the number
   of colours which the palette can be set to produce.

   A common example would be a palette of 256 colours
   (i.e. addressed by eight-bit pixel values) where each colour
   can be chosen from a total of 16.7 million colours (i.e. eight
   bits output for each of red, green and blue).

   Changes to the palette affect the whole screen at once and can
   be used to produce special effects which would be much slower
   to produce by updating pixels.

   (1997-06-03)