The word Coustically is misspelled against Caustically, an adverb meaning "In a caustic manner."
-->
Word contains consecutive vowels 'AU' in between alphabets c & stically is misspelled as 'OU'
Wrong Spelling:  c-ou-stically 
Correct Spelling:  c-au-stically 
Check more misspelled words of Caustically to spell it correct.