|Function:||adjectival (hypocoristic?, patronymic?)|
Adjectival k-suffix, indicating appurtenance; -āk- through resegmentation (cf. -ik- and -uk-). See Russell 1990: 8–12 for the IE evidence. In Celtic, lexical and onomastic Ir. -ach, MW -awc, ModW -og, OBret. -ec (Insular Celtic material in Russell 1990). Frequent in Continental Celtic personal names and toponyms, also in ethnonyms mainly in Celtiberian (Continental Celtic material in Russell 1988; Lambert 1994: 34 f., 39). In Continental Celtic PNN, the exact function is unclear: occurrences of names in -ak- following a PN in Gaulish (G-203, G-118, G-28 -i̯ako-) may indicate patronymic function, but the frequency of individual names derived with -ak- suggests that the suffix could also be used to form hypocoristics (Russell 1988: 136–138, Russell 1990: 18–21).
Only one certain attestation in Cisalpine Celtic (Gaulish) so far, but cf. Lejeune 1974: 50–57 and Russell 1988: 157–161 on the possible influence of Celtic adjectival k-suffixes on the productivity of such suffixes in Venetic onomastics.
Long ā is demonstrated by W -awc/-og, the Gallo-Romance evidence, and the treatment of -acus in Latin verse (Russell 1988: 133).