the world > matter > colour > named colours > blue or blueness > [adjective] > colour of plagues, hurtful things, etc. (3)
esp. Applied to the complexion or colour of the human body, as affected by cold, or contusion: Livid. Hence black and blae (now altered to black and…
Dark in colour; black or blackish; dusky, swarthy. Livid through suffering or emotion. Obsolete.
Taken as the colour of plagues and other harmful things. Now archaic and literary.