Pixy or Piskey
From Henry Jenner's research it can be stated that the proper form is Pixy.
In Cornish, for some reason or other, it was an almost invariable practice to change t or d (except as an initial - and occasionally even then), to s or z.
The root of pixy is pix; divide the double letter x into its component parts, and you can spell it piks or pics. As it is a Cornish word, one can take it for granted that the final s represents an original t. Restore that and the word becomes pict. Add the y and you get picty, pronounced pixy. The term Pixie is sometimes used incorrectly as a generic term for all British faery folk. According to Brian Froud, The Pixie, also variously known as Pisgie, piskie, pigsey, of Cornwall, is based in the district of Dartmoor.... There's hardly a place on Dartmoor that is not haunted by the green mischievous creatures. They have lent their name to many landmarks, Pixie's Holt, Pixie's Cave, Pixie's Parlour, Puggie Stone (the word Puggie has the same derivation as Puck). They dance in the shadows of the standing stones, or gambol on the tumbling stream edges. Their bells can be heard deep in the heart of the many tors on the moor.
if of earth let the swart mine hold thee,
if a Pixie sink thy ring,
if a Nixie seek thy spring.
Pixies often take the form of hedgehogs, known in dialect as urchins.
If thou'rt of air let grey mist fold thee,
