Herbert Weir Smyth, A Greek Grammar for Colleges

CONSONANTS BEFORE Σ

a. The only stop that can stand before ς is π or κ, hence β, φ become π, and γ, χ become κ. Thus, γραφ-σω, ἀγ-σω become γραπ-σω, ἀκ-σω.

[*] 98. A dental stop before ς is assimilated (σς) and one ς is dropped.

σώμασι bodies for σωμασσι out of σωματ-σι, ποσί feet for ποσσί out of ποδ-σι, ὄρνι_σι birds for ὀρνι_σσι out of ὀρνι_θ-σι. So πάσχω suffer for πασσχω out of παθ-σκω (cp. παθ-εῖν and 126).

a. δ and θ become τ before ς: ποδ-σι, ὀρνι_θ-σι become ποτ-σι, ὀρνι_τ-σι.

[*] 98 D. Hom. often retains σς: ποσσί, δάσσασθαι for δατ-σασθαι (δατέομαι divide).

[*] 99. κ is dropped before σκ in διδα（κ）-σκω teach (διδακ-τός taught).

π is dropped before σφ in βλα（π）σ-φημία_ evil-speaking.

[*] 100. ντ, νδ, νθ before ς form νσς (98), then νς, finally ν is dropped and the preceding vowel is lengthened (37).

πᾶσι all for πανσ-σι out of παντ-σι, τιθεῖσι placing for τιθενσ-σι out of τιθεντ-σι. So γίγα_ς giant for γιγαντ-ς, λύ_ουσι loosing for λυ_οντ-σι, σπείσω shall make libation for σπενδ-σω, πείσομαι shall suffer for πενθ-σομαι (πένθος grief).

[*] 101. a. ἐν in, σύν with in composition are treated as follows:

ἐν before ρ, ς, or ζ keeps its ν: ἔν-ρυθμος in rhythm, ἐν-σκευάζω prepare, ἐνζεύγνυ_μι yoke in.

σύν before ς and a vowel becomes συσ-: συσ-σῴζω help to save. before ς and a consonant or ζ, becomes συ-: συ-σκευάζω pack up, σύ-ζυγος yoked together.

b. πᾶν, πάλιν before ς either keep ν or assimilate ν to ς: πάν-σοφος all-wise, παν-σέληνος or πασσέληνος the full moon, παλίν-σκιος thick-shaded, παλίσ-συτος rushing back.

[*] 102. On ρς see 79 a. λς is retained in ἄλσος precinct. ρς, λς may become ρ, λ with lengthening of the preceding vowel: ἤγειρα I collected, ἤγγειλα I announced for ἠγερ-σα, ἠγγελ-σα.

[*] 102 D. Hom. has ὦρσε incited, κέρσε cut, ἐέλσαι to coop up, κέλσαι to put to shore.