See also: fibber English Noun Fibber (plural Fibbers) (slang, derogatory) An FBI agent. Synonyms: Feeb, Feebie 2016, Steven Lee, Project Sanctuary, page 331:This new ID and the new credit card will throw a wrench in the FBI's machine. Those Fibbers will never know what hit them. Anagrams bibrefWikiwand - on Seamless Wikipedia browsing. On steroids.Remove ads