Omisive or Omissive: How To spell?
The word Omisive is misspelled against Omissive, an adjective meaning "Leaving out; omitting."
Omissive has double "ss" is mispronounced as "s"Remember double 'SS' in between the strings omi & ive which should not be misspelled with single 'S'
Wrong Spelling:  omi-s-ive  Correct Spelling:  omi-ss-ive 
Find more wrongly spelled words of Omissive to spell it well.