The term AT CARP can be broken down into three separate words: ENDO (4 letters), KOI (3 letters), and NAG (3 letters). ENDO is a shortened form of the word 'endodontist, ' which is a type of dentist who specializes in treating diseases of the tooth pulp and root canal therapy. KOI is an abbreviation for the Japanese ornamental fish species known as Cyprinus carpio, which is often kept in outdoor ponds or water gardens. NAG is an acronym for the phrase 'no action required, ' which is used to indicate that no further action is needed on a particular task or issue.