Dictionary.com's Word of the Year is...
locomotor ataxia n.
See tabes dorsalis.
rare neurologic form of tertiary syphilis, involving sensory deficits, loss of neuromuscular coordination, and diminished reflexes. Symptoms of this form of neurosyphilis chiefly affect the legs and may not appear for more than 25 years after the initial infection. Untreated, tabes dorsalis usually makes unassisted walking impossible and severely debilitates the victim.