[ ˌɪgnɪs'fatjʊəs ]
■ noun ( plural ignes fatui ˌɪgni:z 'fatjʊʌɪ , ˌɪgneɪz , 'fatjʊi: ) a will-o'-the-wisp.
Origin
C16: mod. L., lit. 'foolish fire' (because of its erratic movement).
IGNIS FATUUS
Meaning of IGNIS FATUUS in English
Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004