Astesm or Asteism: How To spell?

The word Astesm is misspelled against Asteism, a noun meaning "Genteel irony; a polite and ingenious manner of deriding another."

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