Scrap, n.
Etymology: [OE. scrappe, fr. Icel. skrap trifle, cracking. See Scrape, v. t.]
1. Something scraped off; hence, a small piece; a bit; a fragment; a detached, incomplete portion. I have no materials -- not a scrap. De Quincey.
2. Specifically, a fragment of something written or printed; a brief excerpt; an unconnected extract.
3. pl.
The crisp substance that remains after trying out animal fat; as, pork scraps.
2 more senses
4. pl.
Same as Scrap iron, below. Scrap forgings, forgings made from wrought iron scrap. -- Scrap iron. (a) Cuttings and waste pieces of wrought iron from which bar iron or forgings can be made; -- called also wrought-iron scrap. (b) Fragments of cast iron or defective castings suitable for remelting in the foundry; -- called also founding scrap, or cast scrap.
Shades of meaning
Fernald has no entry of its own for scrap; he lists it under particle.
He lists it without comment; the entries above explain its neighbors.