Words and Proper Names

ro·geinn

8146.
Fortson (Benjamin W.): On ‘double-nasal’ presents in Celtic and Indo-European and a new Irish sound law.
In ZCP 57 (2009–2010), pp. 48–78.
Proposes an alternative explanation for the origin of the Old Irish set of verbs ending in -e(i)nnid/-einn in the present (such as ro·geinn, do·greinn, etc.), rejecting K. McCone's derivation of this verb type from PIE ‘double nasal’ presents (in FS Watkins, pp. 465-476) and arguing instead that -nn- is the regular outcome of *-nd- when it was flanked by non-low front vowels.