-on

gen.pl. ending 3O, in aldaron, aranion, elenion, Eldaron, \#esseron, Ingweron, Istarion, Númevalion, Quendion, Silmarillion, Sindaron, tasarion see Nan-Tasarion, Valion, wenderon, yénion. Normally the ending -on is added to the nominative plural, whether it ends in -i or -r, but some nouns in -ë that would have nominative plurals in -i seem to prefer the ending -ron in the genitive hence \#esseron as the gen. pl. of essë "name", though the nominative pl. is attested as essi and we might have expected the gen. pl. *ession; similarly wenderon, Ingweron.