I was reading Children of Húrin and noticed the subtitle: Narn i Chîn Húrin.
The Sindar language dictionary defines "narn" as:
narn S., N. [nˈɑrn] pl. nern S. [nˈɛrn] n. a tale or a saga, that is told in verse to be spoken and not sung ◇ Ety/374, WJ/313, MR/373, S/412 ◇ OS *narna, CE *nʲarnâ "told"
Given Tolkien and Lewis's relationship and passion for their linguistics, is there any reason to infer that Narnia is a based off a Sindar word?