adjectival compounds with first element ending in -σι-

Greek Homeric Greek and Early Greek Poetry
1

I’m wondering if anyone here knows about the linguistic history of such adjectives as

  • ἑλκεσί-πεπλος ‘pulling (ἕλκω) a robe (πέπλος)’
    ἐννοσί-γαιος ‘shaking (ἐν-ϝόθω ‘push, strike’) the earth (γή)’
    ἐνοσί-χθων ‘shaking (id.) the ground (χθών)’
    τερψί-χορος ‘rejoicing (τέρπω) in the dance (χορός)’

Seems that τερπι-κέραυνος ‘rejoicing in the thunderbolt’ ought to be in here too, even though it lacks the /s/.

Just wondering how the vocalism at the end of the first element is to be explained. If a parallel occurs elsewhere in Indo-European I would really like to know! I am wondering if the first element in these compounds is a verbal noun in *-ti- (cf. βάσις < *gʷm-ti-s ‘a going/coming’). I can’t find anything written about this particular structure anywhere.

I know this isn’t directly Homer-related but a lot of these show up in Homer so I figured I would try asking here. Thank you!

2

https://latin.stackexchange.com/questions/7035/what-cases-were-used-in-compounds

http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0007%3Apart%3D3%3Achapter%3D24%3Asection%3D59%3Asubsection%3D59

[*] Smyth 879. Flectional Compounds.—A compound whose first part is a case form, not a stem, is called a flectional compound (cp. sportsman, kinsfolk): (1) nominative: τρεισ-καί-δεκα thirteen; (2) genitive: Διόσ-κουροι Dioscuri (sons of Zeus), Ἑλλήσ-ποντος Helle’s sea, Πελοπόν-νησος (for Πελοποσ-νησος, 105 a) Pelops’ island; (3) dative: δορί-ληπτος won by the spear; (4) locative: ὁδοι-πόρος wayfarer, Πυλοι-γενής born in Pylus.—From such compounds derivatives may be formed, as Ἑλλησπόντιος of the Hellespont, θεοισεχθρία_ hatred of the gods.