A (transient) name given for the wife of Tulkas in Silmarillion revisions from the 1950s-60s (MR/65-7), who was normally given as Nessa. The second element is vinya “young” (MR/67), but meaning of the initial element is unclear. In a Discord chat on 2022-10-09, Lokyt suggested that Lëa might be derived from √LAY “flourish”.
Quenya
lëa-
な$`C verb. behave
lëa-vinya
feminine name. Lëa the Young
A neoderivation from LEÑ (PE17/74, 159); cp. ëa- < EÑ and tëa- < TEÑ. (We read from the Lambenórë PE17 Quenya Lexicon that the paragraph containing the verb lenga- was "rejected with a pair [of] diagonal strokes".)