Backster or Backstair: How To spell?

The word Backster is misspelled against Backstair, an adjective meaning "Private; indirect; secret; intriguing; -- as if finding access by the back stairs."

Word contains consecutive vowels 'AI' in between alphabets backst & r is misspelled as 'E'
Wrong Spelling: backst-e-r
Correct Spelling: backst-ai-r
Explore spell check of Backstair to spell without errors.