Retrogresively or Retrogressively: How To spell?
The word Retrogresively is misspelled against Retrogressively, an adverb meaning "In a retrogressive manner."
Retrogressively has double "ss" is mispronounced as "s"Remember double 'SS' in between the strings retrogre & ively which should not be misspelled with single 'S'
Wrong Spelling:  retrogre-s-ively  Correct Spelling:  retrogre-ss-ively 
Find more incorrect spellings of Retrogressively to spell right way.