Quenya 

asëa aranion

noun. kingsfoil, asëa of the Kings

The Quenya name of S. athelas “kingsfoil” (LotR/864), a combination of asëa and aranion, the genitive plural of aran “king”, hence = “asëa of the kings” (PE17/49, 100). The exact meaning of asea itself isn’t entirely clear. Tolkien sometimes implied asea was another name of athelas (PE17/148; PE22/166), but the translation “asëa of the kings” seems to imply it was a more general term (?healing herb) and that “kingfoil” was more specifically asëa aranion. For purposes of Neo-Quenya, I prefer to use asea for healing herbs of any kind, and use asëa aranion for the species “kingsfoil”.

Conceptual Development: In Lord of the Rings drafts of the 1940s, Tolkien had ᴹQ. asea aranaite, using a distinct adjective ᴹQ. aranaite “✱kingly, royal” instead of later aranion.

Quenya [LotR/0864; LotRI/Asëa aranion; PE17/049; PE17/100] Group: Eldamo. Published by

Sindarin 

athelas

noun. "kingsfoil", a healing herb brought to Middle-earth by the Númenóreans

Sindarin [LotR/V:VIII] Q athea "benefical, helpful" + CS las "leaf". Group: SINDICT. Published by

athelas

kingsfoil

(a healing plant brought to Middle-earth by the Númenoreans) athelas (pl. ethelais)

athelas

kingsfoil

(pl. ethelais)