A palette is:

a thin board that a painter holds and mixes colour pigments on.
a set of colours put on a palette, or in a more general sense, a particular set or quality of colours.
a designated subset of the total range of colours supported by a computer graphics system. Each colour in the palette is assigned a number, and for each pixel, one of these numbers is stored. This number determines the colour of the pixel. Palettes allow images comprising a small number of colours to be stored using a relatively modest amount of graphics memory. Computer graphics systems using a palette include EGA and VGA (for the IBM PC) and the Tiki 100.
the valve under an organ pipe which is connected to the keyboard(s)—as opposed to the stop valve.
the name of a mannequin humanoid robot designed for the fashion and service industry by Tatsuya Matsui of Flower Robotics, Inc.
A palette should not be confused with the following orthographically distinct items:

palate, the roof of the mouth
pallet, a holder for goods for use with a forklift