marconatrix wrote:Welsh modreb 'aunt' and the name Modron, along with Irish ma:thair both point to a root *ma:tr-.
How did this decline in Common Celtic. I.e. where does the long /i:/ in the second syllable of the nom.sing. come from? (I would have reconstructed something like /ma:tri(:)/). It seems odd that a long vowel should be syncopated in British, especially as this would have been the stressed vowel before the accent shift (end of Old Welsh etc.)
The nominative singular was *
mātīr, a fully regular reflex of the PIE hysterodynamic proto-form *
*méh2tēr. The accusative
materan is attested in Gaulish, again a fully regular reflex of the PIE *
*méh2terṃ. The oblique stem, however, was *
mātr- (again a fully regular etc...), and it is the oblique stem used in composition. Thus with an augmentive suffix we have *
mātronā, which regularly gives W.
Modron, with no syncopation. The prehistory of
modreb is somewhat more obscure, and is probably not a Proto-Celtic formation. With an obscure derivational affix *-
kʷih2 added to the PIE root, we have *
méh2tṛkʷih2, the regular outcome of which would be *
mātrikʷī in PC (and thus
modreb, etc.).
For what it's worth, the OI
máthir points not to a proto-form of *
mātr-: rather it can only be from *
mātīr.