Decasylabic or Decasyllabic: How To spell?
The word Decasylabic is misspelled against Decasyllabic, an adjective meaning "Having, or consisting of, ten syllables."
Decasyllabic has double "ll" is mispronounced as "l"Remember double 'LL' in between the strings decasy & abic which should not be misspelled with single 'L'
Wrong Spelling:  decasy-l-abic  Correct Spelling:  decasy-ll-abic 
Find more wrongly spelled words of Decasyllabic to spell it well.