chemical similarity Reference Libraries
A rare earth is an oxide of a rare earth element. Often rare earth elements themselves are loosely called "rare earths". As to exactly what is a "rare earth" element is a matter of some ambiguity. The narrowest definition restricts it to the lanthanides, which are lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium,...
- A person who stands up for something, as contrasted to a bystander who remains inactive.
- One of the upright handlebars on a traditional Inuit sled.