Cappello, Cepparello, Ciapperello, Ciappelletto - what's it all about?

Question

Day 1 Story 1 of the Decameron is about a very bad man who makes a false confession just before his death and ends up being lauded as a saint. This man goes by many closely related names, but I don't understand what they all mean or the connections between them:

After long pondering the matter, he recollected one Ser Ciapperello da Prato, who much frequented his house in Paris. Who being short of stature and very affected, the French who knew not the meaning of Cepparello, but supposed that it meant the same as Cappello, i. e. garland, in their vernacular, called him not Cappello, but Ciappelletto by reason of his diminutive size; and as Ciappelletto he was known everywhere, whereas few people knew him as Ciapperello.

_{-- Rigg translation}

E sopra questa essaminazione pensando lungamente stato, gli venne a memoria un ser Cepparello da Prato, il quale molto alla sua casa in Parigi si riparava; il quale, per ciò che piccolo di persona era e molto assettatuzzo, non sappiendo li franceschi che si volesse dir Cepparello, credendo che 'cappello', cioè 'ghirlanda' secondo il lor volgare a dir venisse, per ciò che piccolo era come dicemmo, non Ciappello, ma Ciappelletto il chiamavano: e per Ciappelletto era conosciuto per tutto, là dove pochi per ser Cepperello il conoscieno.

_{-- Italian original}

There's four slightly different names here: Cappello, Cepparello, Ciapperello, Ciappelletto. What do they mean, why is Ciapperello known as Ciappelletto, and is this significant or interesting with respect to his characterisation?

Answer 1

Cepparello is the real name of this character, someone who, according to some documents found in Prato, seems to have really existed. See, for instance, the notes to the BUR version of the Decameron (Italian original), edited by Amedeo Quondam, Maurizio Fiorilla and Giancarlo Alfano:

Cepparello da Prato: un Cepparello o Ciapparello Dietaiuti da Prato è documentato alla fine del Duecento nei suoi rapporti con Filippo il Bello e Bonifacio VIII (è ancora in vita nel 1304)

My translation:

Cepparello da Prato: someone called Cepparello or Ciapparello Dietaiuti from Prato is documented at the end of the thirteenth century in his relations with Philip the Fair (the king Philip IV of France) and pope Boniface VIII (he is still alive in 1304).

You can find in the Panlessico italiano, ossia Dizionario Universale della lingua italiana, an Italian dictionary edited in 1839 by Marco Bognolo, that Ciappo is a hypocorism of the name Jacopo, which is an archaic version of Giacomo, an Italian name corresponding to English James:

CIAPPO, sm Nome proprio maschile, accorc. ed alterato da Jacopo.

In the text you have quoted this character is described as someone of short of stature: this is why his name is ended with the suffix -ello, which in Italian has a diminutive value, sometimes also derogative.

As your quote shows, he frequented Paris. But French people who knew him didn't understand what Cepparello meant. For this reason, according to the notes to the above mentioned edition of the Decameron,

credendo che nel loro volgare significasse “cappello” o “ghirlanda”’ (cioè, diminutivo di chapel, chapelet: “cappello”, “cappellino”; ma anche “ghirlanda” da poggiare sulla testa: dopo I 16 sarà usato sempre e solo in questa forma a testo, perché è quella con cui il personaggio è conosciuto ovunque)

That is, because of their own vernacular language, the French believed that such a name was a diminutive of chapel, which could be translated in Italian as cappello or ghirlanda (a hat or a garland for the head). Now, French chapel is pronounced in a similar way to Italian Ciappello (an invented name). But, since he had such a short of stature, they added -etto, another Italian suffix with diminutive value, and called him Ciappelletto.

This note also explains that after this sentence of the story

So Musciatto, having bethought him of this Ser Cepparello, with whose way of life he was very well acquainted, judged him to be the very sort of person to cope with the guile of the Burgundians

the protagonist is always called Ciappelletto because it's the name by which the character is known everywhere.

As you have mentioned in a comment, Ciapperello never appears in the Italian original text.

Answer 2

This is my interpretation: The protagonist is an Italian who works in France. He is a short man. His real name is Cepperello (obsolete dimunutive of Jacopo). Cepperello is a word very similar to what the diminutive of Cappello (Italian word for "hat") would be for the French: Ciappelletto (French distortion of Cappelletto, "little hat"). So he was known as Ciappelletto (little hat) and not as Cepparello (little Jacopo).

Jacopo = normal Italian name;
Ciapo = Italian distortion of Jacopo;
Cepparello = Little Ciapo = Little Jacopo (Italian);
Cappello = Hat (Italian);
Cappelletto = Little Hat (Italian);
Ciappello = French distortion of Cappello;
Ciappelletto = French distortion of Cappelletto (little hat).