出典:Wiktionary
Probably per- (“completely”) + fīnītiō (“a determining”, “an assigning”).
Third declension.
| Case | Singular | Plural |
|---|---|---|
| nominative | perfīnītiō | perfīnītiōnēs |
| genitive | perfīnītiōnis | perfīnītiōnum |
| dative | perfīnītiōnī | perfīnītiōnibus |
| accusative | perfīnītiōnem | perfīnītiōnēs |
| ablative | perfīnītiōne | perfīnītiōnibus |
| vocative | perfīnītiō | perfīnītiōnēs |