The English prefix caco- comes from a Latinized form of Greek kakos, “bad, evil.” The English prefix mal- derives from Latin malus, “bad, evil.”
A familiar “caco” word in English is cacophony, which combines “bad” with phone, “sound.” One meaning of cacophony is “the use of harsh sounding words or phrases.” For example: “There are sounds in Gaelic which, though not guttural, are cacophony itself to English ears.”
In the context of speech, the opposite of cacophony is euphony. Literally “good sound,” euphony is the quality of having a pleasant sound.
Cacophony can also refer to a discordant combination of sounds produced in a musical context: “The song explodes into a grating cacophony of grimy analog synths.”
Apart from speech and music, cacophony is used to refer to any unpleasant combination of noises or to a confused variety of anything. For example:
[During the Nazi occupation of Paris] the cacophony of daily urban engagement — passersby, hawkers, street minstrels and performers, construction work, and especially traffic noise — was severely diminished.
This [daily market] was a proper, brick, glass and wrought-iron hangar which stacked up the genuine southern France in a red-blooded cacophony of sensual abundance.
Note: When the context relates to sound, the word cacophony is sufficient. Modifying the word with “of sound” in the following headline is unnecessary because the context clearly relates to musical sound: “Justin Timberlake’s New Song ‘Suit & Tie’ is a Cacophony of Sound.”
The main use of the prefix caco- in English is in the area of medical terminology. It’s combined with other Greek or Latin elements to create words to describe the bad state of bodily organs, for example:
cacoglossia: putrid state of the tongue (glossia=tongue)
cacophthalmia: malignant inflammation of the eyes (ophthalmos=eye)
English words that begin with the other bad prefix—mal- (“bad, badly”)—are numerous.
According to the Online Etymology Dictionary, most Modern English words with this prefix are 19th century coinages. Here are just a few:
maladroit: clumsy, the opposite of adroit.
malapropism: the ludicrous misuse of words, especially in mistaking a word for another resembling it. The word is an eponym, derived from a character in a play. The character’s name, “Mrs. Malaprop,” is a combination of mal+appropriate. One of her lines is, “Illiterate him, I say, quite from your memory.” She’s reaching for the word obliterate.
malaria: a disease spread by mosquitoes. The name originates from a belief that diseases were caused by bad air. Malaria is an Italian borrowing: mal+aria (air).
malediction: a curse. Latin mal+dicere (to speak).
maleficent: given to evildoing. Maleficent is the name of an evil Disney character. In the 1959 film Sleeping Beauty, Maleficent is unambiguously evil. I expect that in the new film, she’s just misunderstood.