Terasyllable or Terrasyllable: How To spell?
The word Terasyllable is misspelled against Terrasyllable, a noun meaning "A word consisting of four syllables; a quadrisyllable."
Terrasyllable has double "rr" is mispronounced as "r"Remember double 'RR' in between the strings te & asyllable which should not be misspelled with single 'R'
Wrong Spelling:  te-r-asyllable  Correct Spelling:  te-rr-asyllable 
Explore spell check of Terrasyllable to spell without errors.