From The Collaborative International Dictionary of English v.0.48:
Blotch \Blotch\, n. [Cf. OE. blacche in blacchepot blacking pot,
akin to black, as bleach is akin to bleak. See Black, a.,
or cf. Blot a spot.]
1. A blot or spot, as of color or of ink; especially a large
or irregular spot. Also Fig.; as, a moral blotch.
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Spots and blotches . . . some red, others yellow.
--Harvey.
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2. (Med.) A large pustule, or a coarse eruption.
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Foul scurf and blotches him defile. --Thomson.
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