The Greek word for the moon is σελήνη selēnē, σελᾱνᾱ selānā, or σελάννᾱ selánnā, depending on dialect. All seem to come transparently from the same root as σέλας sélas, "shine".

But since these both appear to be native words (hence the varying across dialects), why do they show initial /s/? I was taught that initial /s/ before a vowel became /h/ in early Greek, hence cognates sept- versus hept-, semi- versus hemi-, and so on.

  • @AlexB. The problem is that this "s" is not mobile. It is always there. – fdb Mar 9 '18 at 11:20
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    Mea culpa, not Beekes'! Same link, Pre-Greek Loanwords in Greek: "15. A σ occurs both word‑initially and between vowels, where it has disappeared in most inherited words. Initial: σάρυττα, σαγύριον, σάναπτιν, σάνδαλον, σαρρυφθεῖν, σεκούα, σιβύνη, σίγυμνον. Intervocalic: ἀγασυλλίς, ἄγχουσα (ἔγχ‑), αἴθουσ(σ)α, αἱμασιά, αἴσακος, ἄλεισον, δρόσος. After resonant: ἄλσος, βάλσαμον, γελσόν, γένσιμος, μάρσιππος (-υππος)." – Alex B. Mar 9 '18 at 22:02

The usual explanation (e.g. in Beekes) is that selēnē is a Greek formation from selas “light”: *selas-nā > selēnē, with the same suffix (and the same semantics) as in Latin *luk-nā > lūna. For selas there is no adequate etymology and it may well be non Indo-European (borrowing or pre-Greek substrate).


There are AFAIK no outer relations for the Greek words σέλας sélas and σελήνη selēnē attested.

This leaves two possibilities:

  • The words are early loans into Proto-Hellenic from an unknown source language
  • The words can still be inherited from Proto-Indogermanic (and just died out in the other branches) and the proto-word started in a more complicated consonant cluster like /ks/. Under such circumstances, an initial /s/ in Greek can be obtained. An example for this is the prefix συν- that is also found as old Att. ξύν-.
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    Good answer! Are there other examples of initial #sV coming from each of these methods? – Draconis Mar 8 '18 at 17:44
  • Of ξύν, Wiktionary says "-υ- < *-o- is expected, but -σ- < *-s- and -σ- < *-ξ- are not". I don't have enough knowledge of Proto-Greek to say, but is *ks- > *s- a regular sound change? – Draconis Mar 12 '18 at 21:49

fdb already wrote that there is no adequate Indo-European etymology and most likely it is a loan from the Pre-Greek substratum. That being said, another etymology has been in circulation for many decades - its connection to the word 'sun' in PIE (i.e. *séh2u̯el-; see below). This is what Michel Lejeune wrote in his "Phonétique historique du mycénien et du grec ancien" (1972/2017, p. 135):

"L'altération de *sw ancien est donc établie par une série d'exemples sûrs. Cependant, on a supposé que, dans quelques racines, le grec aurait conservé le groupe ancien *sw- (comme il aurait, dans quelques racines, conservé le groupe *sm-, §113); aux approches de l'époque historique, ϝ se serait amuï dans ce groupe initial, ainsi réduit a σ: par example dans σέλας "éclat" qu'on rapproche de skr. svargáḥ "ciel" [...]. Mais, de ces rapprochements possibles, aucun ne s'impose; ces termes, comme la plupart des mots grecs commençant par σ- devant voyelle, demeurent obscurs. Emprunts?"

cf. Sihler (1995) "the usual etymon, PIE *swelH- 'gleam', is well-attested, but G σ- < *sw is hard to accept" (p. 216; emphasis mine - A.B.).

That being said, different Indo-European cognates have been suggested - the following is mentioned in NIL under PIE *séh2u̯el- 'sun':

  • Avestan xvarənah- 'glory, splendour' (Bader 1995, Janda 2004);
  • Vedic (Sanskrit) sauvá- 'belonging to the Sun' (Darms 1978),

cf. "Anschluß von gr. σέλας n. 'Licht, Glanz' (Il.+) und/oder aav. jav. xvarənah- n. ~ 'Ruhmesglanz' an das Word für 'Sonne' wurde oft erwogen" (NIL, p. 611, note 16).

Since the Indo-Iranian languages are not my area of expertise, we'll have to wait for someone else (e.g. fdb) to comment on that.

  • This seems interesting, but unfortunately I don't speak French. – Draconis Mar 9 '18 at 23:08
  • @Draconis Basically, it says that it is possible that in some words *sw might have been preserved (i.e. we end up with PIE *sw > Greek s), we could posit a connection between Greek σέλας and Sanskrit svargáḥ 'heaven'; however, because the origin of the Greek words that start with σ- followed by a vowel remains obscure and the connections are not particularly convincing, Lejeune concludes by saying that such words are probably loans ('emprunts'). – Alex B. Mar 9 '18 at 23:37
  • Interesting! Mind adding that to the answer? – Draconis Mar 9 '18 at 23:53
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    I agree with Sihler that Greek s < sw is without parallel. Besides, there is the semantic difficulty of the proposed shift of meaning from “sun” to “moon”. The Greek descendant of *swel-nā seems to be εἵλη “warmth of the sun”. The same root (IE *swel-) is also the source of Avestan xvarənah- according to Almut Hintze, Der Zamyād Yašt, pp. 28-33 (with detailed discussion of other proposals). – fdb Mar 10 '18 at 12:23
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    @fdb and Alex B. That's some excellent information which I wasn't previously aware of! Mind adding all of that into the answer? (I'm not sure of the etiquette in editing answers to your own question.) – Draconis Mar 12 '18 at 21:47

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