noun

• (uncountable) The simplest alkali metal, the lightest solid element, and the third lightest chemical element (symbol Li) with an atomic number of 3. It is a soft, silvery metal.
• (countable) A single atom of this element.
• (pharmacology, uncountable) Lithium carbonate or other preparations of lithium metal used as a mood stabiliser to treat manic depression and bipolar disorders.
• A lithium battery.
• An inactive village in Perry County, Missouri.