Campaniacum
Campaniacum is the etymon inferred from numerous toponyms in France. The Toponymie générale de la France (TGF) derives it from a Roman personal name Campanius and the Gaulish suffix -acum.[1] The -i- (which is important in the phonetic evolution of *Campaniacum) suggests that Campanius is a gens name.[2]
The modern forms differ according to the diverse phonetic evolutions of the local dialects.
- Campagnac (TGF § 7029)
 - Campénéac (Morbihan) (TGF § 7535)
 - Campigny (TGF § 8819)
 - Champagnac (TGF § 7061 and § 7438)
 - Champagnat (TGF § 7612 and § 8480)
 - Champagné (TGF § 8133)
 - Champagneux (TGF § 8537)
 - Champagney (TGF § 7873)
 - Champagny (TGF § 8868)
 - Champigny (TGF § 8868)
 
The initial /ka/ of *Campaniacum became /ʃa/ (written Cha) in most of Gaul, both in langue d'oïl dialects and the northern langue d'oc dialects; but north of the Joret line, and most Langue d'oc dialects (southern one) /ka/ (written Ca-) was preserved.
In the form Champigny, Gaston Zink offered an explanation for the sequence ign in place of the expected agn: before the palatal consonant /ɲ/, the /a/ shifted to /e/, which in turn closed to /i/; Zink points out the parallel form (fungum) campaniolum ('mushroom') which became champegneul in Old French and champignon (with substitution of suffix) in modern French.[3] This shift is restricted to central langue d'oïl.
See also
    
- Champignac
 - Pourceaugnac
 
References
    
- Ernest Nègre, Toponymie générale de la France (TGF), Librairie Droz, 1990.
 - Ernest Nègre
 - Gaston Zink, Phonétique historique du français (French Phonetic History), 1986, page 184.