Origin: popularized by Sir Walter Scott < error in printed text (1596) by William of Malmesbury, for ME nithing (< ON nithingr), mean person, coward
See niddering in American Heritage Dictionary 4
Origin: Misreading of Middle English nithing
Origin: , from Old English nīthing
Origin: , from Old Norse nīdhingr
Origin: , from nīdh, scorn.