As used in this chapter:
(a) "Junk" means old or scrap copper, brass, rope, rags, batteries, paper, rubber, junked, dismantled or wrecked automobiles or parts thereof, iron, steel and other old or scrap ferrous or nonferrous materials which are not held for sale for remelting purposes by an establishment having facilities for processing such materials.
(b) "Junk yard" means an establishment or place of business, other than an establishment having facilities for processing iron, steel or nonferrous scrap and whose principal product is scrap iron and steel or nonferrous scrap for sale for remelting purposes, which is maintained or operated for the purpose of storing, keeping, buying or selling junk, or for the maintenance or operation of an automobile graveyard, except an establishment or place where automobiles, wrecked or otherwise, are held or impounded for a period not to exceed ninety days exclusively for storage, repair or resale without alteration.