Herbert Weir Smyth, A Greek Grammar for Colleges

COMPENSATORY LENGTHENING

a. Thus are formed κτείνω I kill for κτεν-[ιγλιδε]ω, φθείρω I destroy for φθερ-[ιγλιδε]ω, δότειρα giver for δοτερ-[ιγλιδε]α, κλί_νω I lean for κλιν-[ιγλιδε]ω, ὀλοφύ_ρω I lament for ὀλοφυρ-[ιγλιδε]ω.

b. α becomes η in the σ-aorist of verbs whose stems end in λ, ρ, or ν, when not preceded by ι or ρ. Thus, ἐφαν-σα becomes ἔ-φηνα I showed, but ἐπεραν-σα becomes ἐπέρα_να I finished. So σελήϝη moon for σελασ-νη (σέλας gleam).

c. The diphthongs ει and ου due to this lengthening are spurious (6).

[*] 37 D. 1. Ionic agrees with Attic except where the omitted consonant was ϝ, which in Attic disappeared after a consonant without causing lengthening. Thus, ξεῖνος for ξένος stranger, εἵνεκα on account of (also in Dem.) for ἕνεκα, οὖρος boundary for ὅρος, κοῦρος boy for κόρος, μοῦνος alone for μόνος. These forms are also used generally in poetry.

2. Doric generally lengthens ε and ο to η and ω: ξῆνος, ὧρος, κῶρος, μῶνος. So μῶσα muse from μονσα for μοντ[ιγλιδε]α, τώς for τόνς the, ἠμί am for ἐσμι, χηλίοι 1000 for χεσλιοι, Ionic χείλιοι. (In some Doric dialects ϝ drops as in Attic (ξένος, ὅρος); and ανς, ονς may become α^ς, ος: δεσπότα^ς lords, τός the.)

3. Aeolic has αις, εις (a genuine diphth.), οις from ανς, ενς, ονς. Thus, παῖσα all (Cretan πάνσα, Att. πᾶσα), λύ_οισι they loose from λύ_οντι. Elsewhere Aeol. prefers assimilated forms (ἔμεννα, ἔκλιννα, ξέννος, ἔννεκα, ὄρρος, ἔμμι, χέλλιοι). But single ν, ρ are also found, as in κόρα_, μόνος. Aeolic has φθέρρω, κλίννω, ὀλοφύρρω; cp. 37 a.

[*] 38. α_ arises from αι upon the loss of its ι (43) in ἀ_εί always (from αἰεί), ἀ_ετός eagle (αἰετός), κλά_ει weeps (κλαίει), ἐλά_α_ olive-tree (ἐλαία_, cp. Lat. oliva).

a. This change took place only when αι was followed by ϝ (αἰϝεί, αἰϝετός from ἀϝιετος, κλαιϝει from κλαϝιει, 111, 128) or ι (Θηβα_ίς the Thebaïd from Θηβαιίς); and only when ϝ or ι was not followed by ο.