The authors agree that this surname derives from the personal name of Hebrew-Aramaic origin. F. Miranda describes it as coming from Bar Talmay, with two possible interpretations: "son of the one who conquers" —connecting with the Greek Ptolemaios— or "son of the peasant", according to the Aramaic meaning of the root. A. Bongioanni agrees on the Aramaic origin and notes that it is equivalent to "son of Ptolemy", a name that in turn would mean "valorous".

Bongioanni documents a broad network of popular forms and regional derivatives. In Piedmont, from the variant Bertrumé arises the form Trumlin. The Lombard-Venetian forms Bartolo and Berto are easily confused with the roots Ber, Bértol and Bértul. By contraction appear Bartocci, Bartoccini and Bartozzi. The surname Timeús or Timeúz is peculiar to the Carnia area and is documented in the 14th century; in Trieste it is pronounced Timéus.

Among the regional derivatives that Bongioanni records are: the Tuscan Tolomei; the Cadore Talamini; Talamazzo and Talammazzi in the Padua, Bologna and Cremona areas; the Vicenza forms Bartlomasi, Bartlomazzo, Bartolaso and Bartolazzo; the Lombard Lomazzo. In Friuli, from the roots Bar, Ber and Bórtul, derive Tolazzi, Tolussi, Tolusso, Tulissi and Tulizzi.

Miranda notes that the surname is spread across around 240 municipalities of Italy and has notable presence in southern Italy, especially in Lazio, Molise, Puglia, Basilicata, Campania and Sicily, where it appears in provinces such as Agrigento, Caltanissetta, Messina, Palermo, Enna, Catania and Ragusa, as well as Calabria, Lombardy, Piedmont, Tuscany and Veneto.