noun
Chemistry term referring to rare-earth elements or their compounds. Often used in compounds like 希土類 (rare earths).
希土類元素はハイテク製品に不可欠だ。
Rare-earth elements are essential for high-tech products.
希土類 is the more common compound meaning 'rare earths' as a group; 希土 alone is less frequent and often appears in technical contexts.
From 希 (rare) + 土 (earth), a direct translation of the English 'rare earth'. The spelling 稀土 uses the older character 稀 for 'rare'.