An Etymological Dictionary of Astronomy and Astrophysics

The outer edge, border, margin, or brink of something, especially of a circular object.

Etymology (EN): M.E., from O.E. -rima (in compounds, as in særima “seashore”); cognate with O.Norse rimi “raised strip of land, ridge”

Etymology (PE): Labé “limb, edge,” from lab “lip;” Mid.Pers. lap; cognate with L. labium, E. lip; Ger. Lefze.