From Old Norse opinn, from Proto-Germanic *upanaz. Compare Faroese opin, Norwegian open, åpen, Danish åben, Swedish öppen, Dutch open, Low German apen, open, German offen, West Frisian iepen, English open.
opinn (comparative opnari, superlative opnastur)
| strong declension (indefinite) |
singular | masculine | feminine | neuter |
|---|---|---|---|---|
| nominative | opinn | opin | opið | |
| accusative | opinn | opna | ||
| dative | opnum | opinni | opnu | |
| genitive | opins | opinnar | opins | |
| plural | masculine | feminine | neuter | |
| nominative | opnir | opnar | opin | |
| accusative | opna | |||
| dative | opnum | |||
| genitive | opinna | |||
| weak declension (definite) |
singular | masculine | feminine | neuter |
| nominative | opni | opna | opna | |
| acc/dat/gen | opna | opnu | ||
| plural (all-case) | opnu | |||
| strong declension (indefinite) |
singular | masculine | feminine | neuter |
|---|---|---|---|---|
| nominative | opnastur | opnust | opnast | |
| accusative | opnastan | opnasta | ||
| dative | opnustum | opnastri | opnustu | |
| genitive | opnasts | opnastrar | opnasts | |
| plural | masculine | feminine | neuter | |
| nominative | opnastir | opnastar | opnust | |
| accusative | opnasta | |||
| dative | opnustum | |||
| genitive | opnastra | |||
| weak declension (definite) |
singular | masculine | feminine | neuter |
| nominative | opnasti | opnasta | opnasta | |
| acc/dat/gen | opnasta | opnustu | ||
| plural (all-case) | opnustu | |||