Gibering or Gibbering: How To spell?
The word Gibering is misspelled against Gibbering, which is present continuous of "Gibber"
Gibbering has double "bb" is mispronounced as "b"Remember double 'BB' in between the strings Gi & ering which should not be misspelled with single 'B'
Wrong Spelling:  Gi-b-ering  Correct Spelling:  Gi-bb-ering 
Find more wrongly spelled words of Gibbering to spell it well.