means A hard, creamy-white material from the tusks of elephants and some other animals, prized for carving and once used for piano keys, dice, and ornaments.

from From Latin 'ebur,' meaning ivory or elephant, which passed through Old French as 'ivurie' before settling into English. The Latin itself is thought to be borrowed, possibly from an Egyptian or African source — fitting, since the elephants were too. The phrase 'ivory tower' came much later, from a 19th-century French critic describing a poet's lofty detachment.