Spurious diphthong

A spurious diphthong (or false diphthong) is an Ancient Greek vowel that is etymologically a long vowel but written exactly like a true diphthong ει, ου (ei, ou).^[1]

Origin

A spurious diphthong has two origins: from compensatory lengthening of short ε, ο (e, o) after deletion of a consonant or contraction of two vowels:^[2]

1. • μόντ-ι̯α → μόνσα^[3] (assibilation from palatalization) → μοῦσα "muse"
   • δοτερ-ι̯α^[4] → δότειρα "giver" (feminine; compare masculine δοτήρ)
2. • φιλέ-ετε → φιλεῖτε "you (pl.) love"
   • νόος → νοῦς "mind"

In general, spurious ει, ου contracts from ε, ο + ε, ο, ει, ου. The specific rules are more complex.

True diphthongs

By contrast, true diphthongs are e or o placed before i or u. Some come from e-grade of ablaut + i, or o-grade + u, co-existing beside forms with the other grade:

• λείπω "I leave" (e-grade: genuine diphthong) — λέ-λοιπα "I have left" (o-grade)
• ἐλεύ(θ)σομαι "I will come" (e-grade) — Homeric εἰλ-ήλουθα "I have come" (o-grade)^[5][6]

Pronunciation

Early in the history of Greek, the diphthong versions of ει and ου were pronounced as [ei̯, ou̯], the long vowel versions as [eː, oː]. By the Classical period, the diphthong and long vowel had merged in pronunciation and were both pronounced as long monophthongs [eː, oː].

By the time of Koine Greek, ει and ου had shifted to [iː, uː]. (The shift of a Greek vowel to i is called iotacism.) In Modern Greek, distinctive vowel length has been lost, and all vowels are pronounced short: [i, u].

Other dialects

Long e or o existed in two forms in Attic-Ionic: ει, ου and η, ω (ē, ō). In earlier Severer Doric, by contrast, only η, ω counted as a long vowel, and it was the vowel of contraction.^[7] In later forms of Doric, it contracted to ει, ου. Throughout the history of Doric, compensatory lengthening used η, ω.^[8]

"Severe" refers to the sterner-sounding open pronunciation of η, ω [ɛː, ɔː], in contrast to the closer ει, ου [eː, oː].

References

1. Herbert Weir Smyth, Greek Grammar, par. 25: diphthongs
2. Smyth, par. 6: genuine and spurious ei, ou
3. Smyth, par. 113: τι̯, θι̯ → σ(σ)
4. Smyth, par. 221: -ya in short-a feminine
5. ἔρχομαι. Liddell, Henry George; Scott, Robert; A Greek–English Lexicon at the Perseus Project
6. Smyth, par. 36: vowel-grades
7. Smyth, par. 59 note 5: Severer Doric εε → η; οο, εο → ω
8. Smyth, par. 37 note 2: Doric compensatory lengthening