Necesity or Necessity: How To spell?
The word Necesity is misspelled against Necessity, a noun meaning "That which is necessary; a necessary; a requisite; something indispensable; -- often in the plural."
Necessity has double "ss" is mispronounced as "s"Remember double 'SS' in between the strings nece & ity which should not be misspelled with single 'S'
Wrong Spelling:  nece-s-ity  Correct Spelling:  nece-ss-ity 
Find more wrongly spelled words of Necessity to spell it well.