2019-3-4 · (geology) A very thin ridge of rock. 2004, Richard Fortey, The Earth, Folio Society 2011, p. 88: In his old department in Zürich, they sit in glass cases: models to the life of the peaks he had studied, with the strata painted beautifully and accurately, passing over arête and valley alike.··(zoology) bone (of a fish), fishbone edge (of an object ...