The term 'Source of Ivory' can be answered by two crossword solutions: TUSK (4 letters) and Warthog (7 letters). TUSK is a hard, ivory-colored substance that grows out of the mouths of certain animals, such as elephants, walruses, and narwhals. Warthogs are large, wild pigs found in Africa that have two pairs of tusks protruding from their mouths. Both tusks and warthogs are sources of ivory, which is a valuable material used to make jewelry, sculptures, and other decorative items.