DAEDRIC FUN TIP:
All beings within Mundus are but characters on the stage of fate and should be tagged as such with "character:" before their names.

monochrome

Any image composed of one colour. Whether it's black and white, blue and white, red and white or anything else and white, as long as it's lacking color variety, it's monochrome.

Note:
Images that fit the above description but have color elsewhere (such as the example below) are still considered monochrome as we're only really interested in the subject of the image. Not the unrelated parts that may have also been photographed.