Steorcase or Staircase: How To spell?

The word Steorcase is misspelled against Staircase, a noun meaning "A flight of stairs with their supporting framework, casing, balusters, etc."

Word contains consecutive vowels 'AI' in between alphabets st & rcase is misspelled as 'EO'
Wrong Spelling:  st-eo-rcase 
Correct Spelling:  st-ai-rcase 
Find more incorrect spellings of Staircase to spell right way.

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