B. Zuanella notes that this surname is today typical of Crostù/Hrastovije, although it probably arrived from Sverinaz/Zverinac —in the comune of Grimacco—, where it was already widespread at the beginning of the 17th century. It derives from a zoonym: the Slavic term čuk (in the Slovene dialect of the Natisone, čiuk), which designates the little owl or scops owl (Latin strix noctua, Italian gufo). According to Zuanella, the nickname was originally applied to a person considered somewhat simple or naive. From the same zoonym also comes the house name Čiuki, present in Mersino Alto, in the comune of Pulfero.

The spelling Chiuch uses the digraph ch to represent the Slovene letter č, following a habitual pattern in the area: this also occurs with surnames such as Chiabudini, Chiabai and Chiacig, which reflect the Slovene forms Čjabudin(i), Čjabaj and Čjacič. E. Rossoni agrees on the Slavic origin of the surname and specifies that it is characteristic of the eastern area of the Udine area, in the region of Friuli-Venezia Giulia.