ataxia /ətak″sē·ə/ [Gk, without order] , an impaired ability to coordinate movement, often characterized by a staggering gait and postural imbalance. It can have many causes, including lesions in the spinal cord or cerebellum that may be the sequelae of birth trauma, congenital disorder, infection, degenerative disorder, neoplasm, toxic substance stroke, or head injury. See also hereditary ataxia. −ataxic, ataxial, adj.