means A soft, pale shade of a color, produced by adding white or reducing saturation — or the chalky crayon-like medium used to make such tints.

from From French pastel, borrowed from Italian pastello, a diminutive of pasta — 'paste' — because the original artist's pastels were made by binding powdered pigment into a soft little paste and drying it into sticks. The same humble Latin pasta that gives us 'paste' and indeed 'pasta' sits at the root; the gentle hues we now call pastel got their name from the soft dough they were once ground from.