The authors agree that this surname is of Piedmontese origin and is linked to a dialect nickname meaning "lizard". E. De Felice specifies that it reflects the Italian adaptation of the Piedmontese term laiö' or laiö'l, with the sense of "lizard", and notes that the surname also extends towards central-western Liguria. He adds that in some cases it may derive from the place name of the same etymon, Laiolo or Laioli, frequent in Piedmont and especially in the Langhe.

E. Rossoni links the nickname to the dialect word lajo, with the sense of "green lizard", and supplies historical documentation: he records the death of one Michele Laiolo in the registers of Tigliole, in the Asti area, dated 27 January 1632. He further notes the existence of a locality called Laioli in Mombercelli, also in the Asti area. As for geographical distribution, Rossoni places this surname mainly in the area between Acqui Terme —in the province of Alessandria— and Asti, while the variant Lajolo, considerably rarer, would have spread above all in Turin, with origins likewise going back to the Asti area.