Greek/Third Declension Greek Nouns
I am working my way through a Greek grammar.
The third declension is interesting.
My question is this: why does the noun πατηρ which has a root πατερ drop the "ε" in the genitive?
I have been taught that when you drop the genitive ending in the third declension, you get the root.
This isn't the case.
Can you explain why this behaves the way it does?
actually the noun πατήρ has three stems: πατηρ (with a long vowel), πατερ (with a short vowel) and πατρ (without vowel).
This noun has in fact an apophony, i.e. a stem alternation with vowel gradation in πατηρ / πατερ / πατρ.
Concerning this, please note that:
1.the stem πατηρ is used only in the nominative singular πατήρ
2.the stem πατρ is used in the genitive and dative singular, as well as in the dative plural where however there is an α between the ρ and the σ because it was impossible to pronounce the three consonants τρσ, so that the stem πατρ before the ending -σι became πατρά-σι
3.the stem πατερ is used in all the other cases of the singular, plural and dual.
As for what you say, i.e. that when you drop the genitive ending in the third declension, you get the root/stem, it is generally true, but not for the STEMS IN ερ, i.e. the nouns in -τηρ such as πατήρ and μήτηρ that show three forms of stem gradation: -τηρ strong, -τερ middle, -τρ weak. Moreover in these nouns the ρ between consonants becomes ρα, as I've already said.
To conclude, the reason why the noun πατήρ, whose three stems are πατηρ, πατερ and πατρ, drops the "ε" in the genitive is that in the genitive this noun uses the stem πατρ (weak gradation).
Hope this is clear enough, despite the difficulty of the matter.