Mastifs or Mastiffs: How To spell?
The word Mastifs is misspelled against Mastiffs, which is plural of "Mastiff"
Mastiffs has double "ff" is mispronounced as "f"Remember double 'FF' in between the strings Masti & s which should not be misspelled with single 'F'
Wrong Spelling:  Masti-f-s  Correct Spelling:  Masti-ff-s 
Find more wrongly spelled words of Mastiffs to spell it well.