nebHos:nebH(e)los - wetos : wet(e)lo - a common trend?

From: Joao S. Lopes
Message: 71733
Date: 2014-05-04

Neuter s-stems like *wetos and *nebHos show derivatives  *wetelo- and *nebHelo-. How to explain this alternative suffixes -s-/-l- (and -t-, if we add *nemeto-)

JS Lopes