(mas.), Nixie (fem.). Kind busy-body. Little creatures not unlike the Scotch brownie and German kobold. They wear a red cap, and are ever ready to lend a helping hand to the industrious and thrifty (See Nick.)
“Another tribe of water-fairies are the Nixes, who frequently assume the appearance of beautiful maidens.” —T. F. T. Dyer: Folk-lore of Plants, chap. vii. p. 90.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894