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