Mightines or Mightiness: How To spell?
The word Mightines is misspelled against Mightiness, a noun meaning "Highness; excellency; -- with a possessive pronoun, a title of dignity; as, their high mightinesses."
Mightiness has double 'ss' in the end mispronounced as 's'Remember double 'SS' appears in the end of this word which should not be misspelled with single 'S'
Wrong Spelling:  mightine-s  Correct Spelling:  mightine-ss 
Find more wrongly spelled words of Mightiness to spell it well.