staving And Rosta:

So let's ask why it became /'dɛʊs/. The phonetic difficulty would have been
the difficulty of having a monosyllabic--disyllabic contrast in a phonetic
monophthong. So given that the phonologically expected vocative would have
been /dɛ/ rather than /dɛ.ɛ/, the vocative would have ended up as a bare
stem. How many vocatives consist of just a bare stem, and how many
vocatives share the form of the nominative? Given that an /ɛ/ suffix was no
longer a phonologically licit option, what was the morphologically least
irregular vocative?


How many vocatives consist of just a bare stem? I think those where the stem ends in i, eg filius => fili. And since the vocative is a marginal case anyway (only existing for masculine group 2 nouns in the singular), it's easy to lose.

Pete Bleackley
The Fantastical Devices of Pete The Mad Scientist -