nasty

From Middle English nasty, nasti, naxty, naxte (“unclean, filthy”), whence also Early Modern English nasky (“nasty”), of obscure origin. Probably from earlier Middle English *naskty, *naskedy, from Middle English *nasked (“dirty, messy”) + -y, ultimately of North Germanic origin (comparable to Danish nasket (“dirty, foul, unpleasant”), Swedish naskot (“dirty, filthy”), Swedish naskig, naskug (“nasty, dirty, messy”)), themselves all probably related to Proto-Germanic *hnaskuz (“tender, soft”). Likely doublet of nesh and nosh. Cognate with Scots nastie, nestie (“dirty, filthy”). Alternative theories have also been proposed, which include: * From Low German nask (“nasty”) + -y. * Middle Dutch nestich, nistich ("nasty, dirty, unpleasant" > Modern Dutch nestig (“dirty, filthy, unclean; lazy, cranky”)), perhaps ultimately connected to the Scandinavian word above, or related to *nest (“nest”). * From Old French nastre (“lowly, strange”), shortened form of villenastre (“infamous, bad”), from vilein (“villain”) + -astre (pejorative suffix), from Latin -aster. * Other suggestions include Old High German naz (“wet”), hardening of English nesh(y) (“soft”), or alteration of English naughty. * Modern use of the word is sometimes attributed to the popular and often derogatory 19th century American political cartoons of Thomas Nast, but the word predates him.

来源：wiktionary