The moon

Apart from those already mentioned, there is another interesting type of
*-s- stem that seems to go back to PIE: derivatives of nouns in
*-no-/*-nah2. Many of them (though not all) are characteristically
social/cultural or legal terms, especially in Indo-Iranian, e.g. Av.
rae:xnah-, Ved. rekn.as- < *loikW-ne-s- 'bequeathed property'; Av.
afnah-, Ved. apnas- 'wealth', perhaps cognate to Gk. apH(e)nos 'wealth'
(also an s-stem), but with examples in Latin as well, e.g. Lat. mu:nus
(moen-), -eris 'service, duty; gift, favour', based on *moi-no-/-nah2
'exchange, countergift' --> *moi-ne-s-. Cf. also Ved. pari:nas- 'plenty,
abundance' < *pelh1-ne-s- (with a new full grade, as in synonymous
pari:man < *pelh1-mn.); Lat. vo/ulnus 'wound' < *welanos < *welh2-ne-s-
(or the like, cf. Gk. [w]oule^ 'scar' < *wolnah2 < *wOlh2-nah2 and Hitt.
walh- 'strike').

It seems likely that the term for 'moon, month', *meh1-no:t-s/-n(e)s-,
with its apparently puzzling suffix, is of the same kind, derived from
*meh1- 'to measure', via *meh1-no- (Ved. ma:na- 'measure,
measuring-cord, standard', cf. Goth. me:l (n.) 'time, season' and n-stem
me:la 'bushel, measure'). A meaning like 'standard unit of time' for
*meh1-ne-s- falls out naturally from the pattern discussed above. It's
the only *-nes- noun in which traces of the *-s-/*-t- alternation can be
observed (courtesy of Germanic-speakers) -- not surprisingly, given its
high frequency of use. It follows, however, that other *-nes- words
contain the same *-s-/*-t- suffix rather than plain *-s-. Any ideas
about the origin of participial *-wot-/*-us-?

Piotr

P.S. I'd now analyse Slavic *meseNcI as *meh1ns-i-ko- > *meHsinko- or
even *meh1ns-ko- > *meHsn.ko-, with a metathetic "repair" of a
phonologically cumbersome sequence.

P.