Akathisia: A movement disorder characterized by a feeling of inner restlessness and a compelling need to be in constant motion as well as by actions such as rocking while standing or sitting, lifting the feet as if marching on the spot and crossing and uncrossing the legs while sitting. People with akathisia are unable to sit or keep still, complain of restlessness, fidget, rock from foot to foot, and pace.

Akathisia is often a side effect of certain drugs. The drugs that can cause akathisia include neuroleptic (antipsychotic) agents, serotonin receptor antagonists, lithium, L-dopa,, calcium channel blockers and phenothiazine antiemetics such as prochlorperazine or metoclopropamide. Also spelled acathisia. From the Greek a- + kathisis, a sitting.