Res or Reis: How To spell?

The word Res is misspelled against Reis, a noun meaning "A common title in the East for a person in authority, especially the captain of a ship."

Word contains consecutive vowels 'EI' in between alphabets r & s is misspelled as 'E' as letter 'I' is phonetically ignored
Wrong Spelling:  r-e-s 
Correct Spelling:  r-ei-s 
Explore spell check of Reis to spell without errors.