1. Any of a series of 15 metallic chemical elements with atomic numbers 57 through 71, including lanthanum and ending with lutetium.
Usage: Also called rare earth element or lanthanide.; These elements are found in the lanthanide series of the periodic table.

1. Of, relating to, or belonging to the lanthanoids.

Examples

• Cerium is a lanthanoid used in catalytic converters.
• The lanthanoid series includes elements essential for modern technology.
• Lanthanoid compounds are important in electronics and renewable energy applications.
• Scientists study lanthanoid properties to develop new materials.
• Erbium, a lanthanoid, is used in fiber optic amplifiers.
• The lanthanoid elements are characterized by their similar chemical behavior.