blot (v.) Look up blot at Dictionary.com
early 15c., "to make blots;" mid-15c. "to blot out, obliterate" (words), from blot (n.). Related: Blotted; blotting.
blot (n.) Look up blot at Dictionary.com
late 14c., originally "blemish," perhaps from Old Norse blettr "blot, stain," or from Old French blot, variant of bloc "block," or blestre "blister, lump, clump of earth."