lithium

1. (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.Examples: "The importance of lithium-ion batteries makes lithium a potentially strategic natural resource."; "Already, beautiful places are being wrecked by an electric vehicle resource rush. Lithium mining, for example, is now poisoning rivers and depleting groundwater from Tibet to Bolivia."uncountable

2. (countable) A single atom of this element.countable

3. (pharmacology, uncountable) Lithium carbonate or other preparations of lithium metal used as a mood stabiliser to treat manic depression and bipolar disorders.Examples: "It seems like his moods are better since he started taking lithium."; "There's more: Part of the reason I am so meek is that I stopped taking my lithium a few weeks before. It's not that I have a death wish, and it's not that I'm like Axl Rose and think that lithium makes me less manly (he supposedly stopped taking it after his first wife told him that his dick wasn't as hard as it used to be and that sex with him was lousy;[…])."; "Lithium has been used as a mood stabiliser for 50 years but its action mechanism is still unclear."uncountable

4. (countable) A lithium battery.countable