An adverb glossed as both “once” and “then” (SD/247, VT24/12). Several authors have suggested (AAD/23, EotAL/TA3) that the final element may be îdô “now”. Andreas Moehn suggested (EotAL/TA3) the initial element tâ is a marker that puts it into the past: îdô = “now”, tâ-îdô = “previous time” = “then”. It seems likelier to me that the prefix is related to the Eldarin demonstrative root √TA “that, there, then”, as suggested by Carl Hostetter and Patrick Wynn (AAD/23): tâ-îdô = “that time” = “then”.
Conceptual Development: In the second draft of the Lament of Akallabêth, this word was ēluk (SD/312).
nëa (1) "once, at one time" (in the past) (VT49:31). Also néya.