From Proto-Italic *-kos, from Proto-Indo-European *-kos, *-ḱos. Cognate with Ancient Greek -κός (-kós), Proto-Germanic *-gaz, Sanskrit -शस (-śasa) and Proto-Slavic *-kъ.
PIE *-ko- on noun stems carried the meaning 'characteristic of, like, typical, pertaining to', and on adjectival stems it acted emphatically.
-cus (feminine -ca, neuter -cum); first/second-declension suffix
This suffix survives in inherited forms and became productive through its derivations (cf. infra) by metanalysis.
First/second-declension adjective.
| Number | Singular | Plural | |||||
|---|---|---|---|---|---|---|---|
| Case / Gender | Masculine | Feminine | Neuter | Masculine | Feminine | Neuter | |
| Nominative | -cus | -ca | -cum | -cī | -cae | -ca | |
| Genitive | -cī | -cae | -cī | -cōrum | -cārum | -cōrum | |
| Dative | -cō | -cō | -cīs | ||||
| Accusative | -cum | -cam | -cum | -cōs | -cās | -ca | |
| Ablative | -cō | -cā | -cō | -cīs | |||
| Vocative | -ce | -ca | -cum | -cī | -cae | -ca | |