kett- + -o, ultimately from kesi, possibly through kettää due to the geminated -tt-
ketto
| Inflection of ketto (Kotus type 1*C/valo, tt-t gradation) | |||
|---|---|---|---|
| nominative | ketto | ketot | |
| genitive | keton | kettojen | |
| partitive | kettoa | kettoja | |
| illative | kettoon | kettoihin | |
| singular | plural | ||
| nominative | ketto | ketot | |
| accusative | nom. | ketto | ketot |
| gen. | keton | ||
| genitive | keton | kettojen | |
| partitive | kettoa | kettoja | |
| inessive | ketossa | ketoissa | |
| elative | ketosta | ketoista | |
| illative | kettoon | kettoihin | |
| adessive | ketolla | ketoilla | |
| ablative | ketolta | ketoilta | |
| allative | ketolle | ketoille | |
| essive | kettona | kettoina | |
| translative | ketoksi | ketoiksi | |
| abessive | ketotta | ketoitta | |
| instructive | — | ketoin | |
| comitative | See the possessive forms below. | ||