Wendigo
In Algonquian folklore, the wendigo () or windigo is a mythical man-eating monster or evil spirit native to the northern forests of the Atlantic Coast and Great Lakes Region of the United States and Canada. The wendigo may appear as a monster with some characteristics of a human or as a spirit who has possessed a human being and made them become monstrous. It is historically associated with murder, insatiable greed, and the cultural taboos against such behaviours.
Indigo
The human eye does not readily differentiate hues in the wavelengths between what we today call blue and violet. If this is where Newton meant indigo to lie, most individuals would have difficulty distinguishing indigo from its neighbors. According to Isaac Asimov, "It is customary to list indigo as a color lying between blue and violet, but it has never seemed to me that indigo is worth the dignity of being considered a separate color. To my eyes it seems merely deep blue."