G. Rohlfs describes this surname as of Greek-Byzantine origin, documented in the province of Reggio Calabria, specifically in Motta San Giovanni, San Lorenzo and the Bova area. He derives it from the Modern Greek χειλᾶς, in turn related to χείλη, "lips", and interprets it as a nickname referring to a person with prominent lips. Rohlfs notes that the form Χειλᾶς survives in Greece as a surname, and mentions as sibling variants Chilla and Chillà.

V. Blunda agrees on the Greek origin and on the descriptive value of the nickname, although he presents the etymological form as cheilàs, derived from the term cheilos, "lip", with the meaning of "man with thick lips". Blunda links this surname with Chillaci and Chillari, which share the same root and appear recorded in contiguous entries. Blunda's geographical reference corresponds to Sicily, which suggests that the surname has independent origins in different regions of Italy.

P. Durante also places it in the Greek sphere, although he proposes with reservations an alternative root: kyllòs, which would mean "curved". The explicit doubt marked by the question mark indicates that this etymology is tentative and not consolidated by the author.