The Genitive-Plural Stress Shift

The genitive plural ALWAYS ends in -ων, and across the whole noun system it is the case that most often MOVES the stress. The course has met this piecemeal (δάσκαλος → δασκάλων, πόρτα → πορτών, όνομα → ονομάτων); here is the single rule. Two things decide whether the stress moves: WHERE it sits in the nominative, and how many syllables the word has. OXYTONE nouns already stress the ending, so nothing moves: αδελφός → αδελφών, οδός → οδών, φοιτητής → φοιτητών. Nouns stressed further back move the tonos TOWARD the ending in the gen pl - either to the PENULT (antepenult-stressed -ος/-μα words: άνθρωπος → ανθρώπων, μέθοδος → μεθόδων, μάθημα → μαθημάτων, όνομα → ονομάτων) or all the way to the ULTIMA (feminine -α and paroxytone -ης words: πόρτα → πορτών, θάλασσα → θαλασσών, μητέρα → μητέρων, ναύτης → ναυτών, εργάτης → εργατών). The safest habit: build the gen pl in -ων, then check the stress landed toward the end - never leave it on the first syllable of a long word (“άνθρωπων” is the classic error; it is ανθρώπων).