An (archaic) word for “ocean”, an augmentative form of airë mentioned in a couple of later notes (PE17/27, 149). A more modern form is ëaron.
Conceptual Development: The form ᴹQ. airen appeared in parenthesis beside ᴹQ. aire “sea” in The Etymologies of the 1930s (Ety/AY). Helge Fauskanger suggested that it might be a genitive form (QQ/airë), but in notes on The Feanorian Alphabet from the 1930s, aire “sea” >> airen (PE22/23 note #70), suggesting it is an alternate (augmentative?) form. If so, it is probably a precursor to airon.
airon noun "ocean" (PE17:27). Also ëaron, q.v.