[shelf] n, pl shelves [ME, prob. fr. OE scylfe; akin to ON hlithskjalf Odin's seat] (14c) 1 a: a thin flat usu. long and narrow piece of material (as wood) fastened horizontally (as on a wall) at a distance from the floor to hold objects b: one of several similar pieces in a closet, bookcase, or similar structure c: the contents of a shelf
2: something resembling a shelf in form or position: as a: a sandbank or ledge of rocks usu. partially submerged b: a flat projecting layer of rock c: the submerged gradually sloping border of a continent or island: continental shelf -- shelf.ful n -- shelf.like adj -- off the shelf : available from stock: not made to order "off the shelf equipment" -- on the shelf : in a state of inactivity or uselessness