The authors agree that this surname derives from a nickname linked to small stature or slight build, formed on the word piccolo ('small'). E. De Felice notes that the word is already documented as Piccolus and Piccolinus from the 10th century, and that the compound Piccolomini is a traditional form still attested in Tuscany, especially in Siena. The surname is diffused throughout Italy, with a high frequency in Veneto, where variants such as Del Piccolo, Piccolìn, Piculìn and Piccolotto appear; in Naples forms such as Lo Piccolo and Lopiccolo are recorded, proper to the far south.

E. De Stefani supplies specific information about the Friulian area: the surname is documented in Carnia —the mountainous zone of northern Friuli, in the province of Udine— from the mid-14th century, with a presence in Tolmezzo, Clauzetto and Socchieve. He further relates as a sister surname Pizzul, which continues the Friulian form pìzzul ('small'), present in Gorizia, Cormons and Mossa. He also mentions Piccilini, a variant of the Friulian picinìn or pitinìn ('tiny'), today rare and documented in Cavazzo Carnico from the mid-16th century.