The word Stifened is misspelled against Stiffened, which is past tense of "Stiffen"
-->
Stiffened has double "ff" is mispronounced as "f"
Remember double 'FF' in between the strings Sti & ened which should not be misspelled with single 'F'
Wrong Spelling: Sti-f-ened
Correct Spelling: Sti-ff-ened
Find more wrongly spelled words of Stiffened to spell it well.