Caern or Cairn: How To spell?

The word Caern is misspelled against Cairn, a noun meaning "A pile of stones heaped up as a landmark, or to arrest attention, as in surveying, or in leaving traces of an exploring party, etc."

Word contains consecutive vowels 'AI' in between alphabets c & rn is misspelled as 'AE'
Wrong Spelling:  c-ae-rn 
Correct Spelling:  c-ai-rn 
Explore spell check of Cairn to spell without errors.

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