noun
(uncountable) The simplest alkali metal, the lightest solid element, and the third lightest chemical element (symbol Li) with an atomic number of 3 and atomic weight of 6.94. 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.
(countable) A lithium battery.