ivory nut

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The seed of the ivory palm, having bony endosperm that is used as a substitute for true ivory.

Century Dictionary and Cyclopedia

1. n. The seed of Phytelephas macrocarpa, a low-growing palm, native of South America. The seeds are produced, 4 to 9 together, in hard clustered capsules, each head weighing about 25 lbs. when ripe. Each seed is about as large as a hen's egg; the albumen is close-grained and very hard, resembling the finest ivory in texture and color; it is hence called vegetable ivory, and is often wrought into ornamental work. It is also known as corozo.

GNU Webster's 1913

1. n. (Bot.) the nut of a species of palm, the Phytephas macroarpa, often as large as a hen's egg. When young the seed contains a fluid, which gradually hardness into a whitish, close-grained, albuminous substance, resembling the finest ivory in texture and color, whence it is called vegetable ivory. It is wrought into various articles, as buttons, chessmen, etc. The palm is found in New Grenada. A smaller kind is the fruit of the Phytephas microarpa. The nuts are known in commerce as Corosso nuts.

WordNet 3.0

1. n. nutlike seed of a South American palm; the hard white shell takes a high polish and is used for e.g. buttons