E. Rossoni considers that this surname derives from the reduced form of the name Nicolò. He notes specific areas of presence in the lower Trentino, in the Foggia area and in the Turin area.

V. Blunda proposes a different etymology: he derives it from the Greek colòs, "lame", with which the person with difficulty in walking was designated. According to this author, the term would have motivated the surname as a descriptive nickname applied to an ancestor for his physical trait, following the habitual patterns of the Sicilian surnames of Greek origin derived from bodily characteristics of the bearer. Blunda documents it in Sicily.

Both proposals are incompatible with each other and respond to different regional traditions: Rossoni's points to a hypocoristic form of a given name very widespread in northern and central Italy, while Blunda's refers to a Greek base linked to the descriptive lexicon peculiar to southern Italy.