40.5 For some declensions, the ending for the MASCULINE or FEMININE SINGULAR VOCATIVE may differ from the NOMINATIVE. In such cases, the vocative is most often formed in one of three ways, none of which offer significant problems of identification:
- 2nd declension: –ος is replaced with –ε
- 3rd declension: the stem is used on its own
- 3rd declension: the stem is shortened to end in an allowable Greek sound
40.6 2nd declension: –ος is replaced with –ε
All masculine (and feminine) nouns/adjectives of the 2nd declension form their vocative with –ε.
- παραδίδως, ὦ ἀδελφέ, τὴν πατρίδα.
- Brother, you are betraying your country.
- ἀδελφός → ἀδελφέ (voc.)