Sibyline or Sibylline: How To spell?
The word Sibyline is misspelled against Sibylline, an adjective meaning "Pertaining to the sibyls; uttered, written, or composed by sibyls; like the productions of sibyls."
Sibylline has double "ll" is mispronounced as "l"Remember double 'LL' in between the strings siby & ine which should not be misspelled with single 'L'
Wrong Spelling:  siby-l-ine  Correct Spelling:  siby-ll-ine 
Find more wrongly spelled words of Sibylline to spell it well.