Clasis or Classis: How To spell?
The word Clasis is misspelled against Classis, a noun meaning "A class or order; sort; kind."
Classis has double "ss" is mispronounced as "s"Remember double 'SS' in between the strings cla & is which should not be misspelled with single 'S'
Wrong Spelling:  cla-s-is  Correct Spelling:  cla-ss-is 
Find more wrongly spelled words of Classis to spell it well.