Colle is specific to the Veneto, Friuli, Bellunese areas above all, to the Treviso area, to the Pordenone area and to the Udine area. Colli seems to have two stocks, in the Milanese and Pavia areas and in the Reggio area, Collo seems to come from Piedmont, one of the many Italian toponyms containing the term Colle, it is also possible, but very unlikely that they derive from the Celtic name Coll. Example of this surname is found in the Diplomatic Code of Medieval Lombardy under the year 1179, where it reads: "... Placuit itaque bona convenit voluntate inter Strimidum qui dicitur Collum, de loco Gudi Antibiagi ...". additions provided by Giovanni Vezzelli Colli is the surname of the medieval personal name Collus, of supernominal origin, from the lat. collum «neck», to indicate the length or thickness out of the ordinary. In a Modenese paper of 1138 a "Albertus qui vocatur Collo.de loco Purcile" is mentioned; another Collus is mentioned as heads in 1165 and an "Andreas Colli" in 1183, etc. Source: F. Violi, Surnames in Modena and in the Modena area.
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