Triennialy or Triennially: How To spell?
The word Triennialy is misspelled against Triennially, an adverb meaning "Once in three years."
Triennially has double "ll" is mispronounced as "l"Remember double 'LL' in between the strings triennia & y which should not be misspelled with single 'L'
Wrong Spelling:  triennia-l-y  Correct Spelling:  triennia-ll-y 
Find more wrongly spelled words of Triennially to spell it well.