Lord of the eagles, translated “Windlord” (LotR/261) or “Lord of the Storm” (LR/301). It is a combination of gwae “wind” and hîr “lord” (PE17/33). It appears that in this name, the older diphthong [ai] was preserved from the primitive ✶waiwa(y) > S. gwae.
Conceptual Development: In Silmarillion drafts from the 1930s, this name first appeared as N. Gwaewar (LR/301), and so appeared in Lord of the Rings drafts from the 1940s (TI/134), though in one place it appeared as Gwaiwar (TI/151). Tolkien eventually changed it to N. Gwaehir >> Gwaihir (TI/430), and it mostly kept this form thereafter, though it occasionally appeared as Gwaehir (MR/410), which would be more in keeping with the usual [[n|revision of [ai] to [ae]]].
gwaew (“wind”) + hîr (“lord”)