I am not sure of the exact definition of blender, but, to me it is a color that blends into the other colors you are using
example: If you have pink, red, yellow roses and wanted another color, you would call on a blender, something with pinkish tones, redish, yellowish. I purchased a blue blender for what I am going to be doing. I can best explain it to be like 2 or 3 shades of blue
this is an example
http://www.craftandfabriclinks.com/s...ed_fabric.html