noun A flat, rigid structure, fixed at right angles to a wall or forming a part of a cabinet, desk, etc., and used to display, store, or support objects.
We keep the old newspapers on the bottom shelf of the cupboard, and our photos on the top shelf.
noun The capacity of such an object
a shelf of videos
noun A projecting ledge that resembles such an object.
noun The part of a repository where shelvesets are stored.
verb Alternative form of shelve.
noun A reef, sandbar, or shoal.
noun ↑ Douglas Harper (2001–2026), “shelf (n.2)”, in Online Etymology Dictionary.