Tetrasylabical or Tetrasyllabical: How To spell?
The word Tetrasylabical is misspelled against Tetrasyllabical, an adjective meaning "Consisting of, or having, four syllables; quadrisyllabic."
Tetrasyllabical has double "ll" is mispronounced as "l"Remember double 'LL' in between the strings tetrasy & abical which should not be misspelled with single 'L'
Wrong Spelling:  tetrasy-l-abical  Correct Spelling:  tetrasy-ll-abical 
Find more wrongly spelled words of Tetrasyllabical to spell it well.