niggle v.

"mean or stingy person, miser," late 14c., nigard, nygard, nygart, also with a variant nigoun, nygun (c. 1300), a word of uncertain origin. The suffix suggests French origin (see -ard), but the root word is possibly from earlier nig "stingy" (c. 1300), which is perhaps from a Scandinavian source related to Old Norse *hniggw, related to hnøggr "stingy," from Proto-Germanic *khnauwjaz (source of Swedish njugg "close, careful," German genau "precise, exact"). Perhaps also related to Old English hneaw "stingy, niggardly," which did not survive in Middle English. A noun nig "niggardly person" is attested from c. 1300, but OED considers this unlikely to be the source of the longer word.