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will–o'–the–wisp

will–o'–the–wisp /ˌwɪləðəˈwɪsp/ noun
will–o'–the–wisp
/ˌwɪləðəˈwɪsp/
noun
Britannica Dictionary definition of WILL–O'–THE–WISP
[noncount]
: a goal that cannot be reached
: a light that sometimes appears at night over wet ground