The correct spelling of the word "cardophagi" is with a "g" at the end, not "j" as it is commonly misspelled. The word comes from the Greek καρδόφαγος (kardophagos), which means "heart-eater". The spelling of the word can be explained using the International Phonetic Alphabet (IPA) as follows: /kɑːdəˈfæɡaɪ/ - the "g" at the end is pronounced as a hard "g" sound, similar to the "g" in the word "go".
The word "cardophagi" is not commonly found in English and does not have a widely accepted etymology. It seems to be a term derived from the Greek word "kardophági", which is a compound of "kardia" (meaning "heart") and "phagein" (meaning "to eat" or "to devour"). In ancient Greek, the term referred to a type of sea urchin that was believed to have a heart-like appearance. However, it is unclear how the term "cardophagi" specifically came into use or if it has any specific meaning in another context.