A word for a mountain range, a compound of S. aeg “sharp” and S. lîr “line”, or more literally “line of (mountain) peaks”, most notably as an element in S. Hithaeglir “Misty Mountains, (lit.) Line of Misty Peaks” (Let/180; RC/11).

Conceptual Development: The earliest iteration of this word was ᴱN. aiglir “peak, mountain top” in Early Noldorin Word-lists from the 1920s, but there it was a singular rather than collective noun, an elaboration of ᴱN. aig “high, steep” (PE13/136, 158). In this period it had a distinct plural form eiglir as in ᴱN. Eiglir Engrin “Iron Mountains” (LB/33, 49). In The Etymologies of the 1930s it appeared as N. oeglir “range of mountain peaks” with essentially the same etymology as given above, except with the Noldorin word N. oeg “sharp” instead of later Sindarin word S. aeg. It appeared as aiglin or aeglin in some earlier versions of the name Hithaeglir (TMME/379; Let/180), but was corrected to aeglir in later versions of The Lord of the Rings.