leprechaun

From Irish leipreachán, luprachán, from Middle Irish luchrupán, from Old Irish luchorpán. See also Irish lucharachán. The word's further etymology is disputed; it is traditionally explained as a compound containing lú (“small”, from Proto-Indo-European *h₁lengʷʰ-) + corp (“body”, which is from Latin corpus). However, an alternative suggestion is that it is a derivative of Latin Lupercī (“priests of Lupercus”), who were misinterpreted as an antediluvian species by medieval Irish scholars.

来源：wiktionary