An Etymological Dictionary of the German Language/Annotated/heikel
heikel, adjective, ‘hooked, captious, nice,’ Modern High German only, but widely current in the dialects; Swiss. heikχel, Bavarian and Suabian haikel, East Frisian hekel, ‘fastidious with regard to food.’ Geographically heifel and Efel seem to supplement each other, and hence may be regarded as identical.