tar·an·tism 
(tărən-tĭz′əm)
(tărən-tĭz′əm)n.
A disorder characterized by an uncontrollable urge to dance, especially prevalent in southern Italy from the 15th to the 17th century and popularly attributed to the bite of a tarantula.
[New Latin tarantismus, after Taranto.]
- underwire
- underwood
- underwool
- underworld
- under wraps
- underwrite
- underwriter
- undescended testicle
- undeserved
- undeservedly
- undesigning
- undesirability
- undesirable
- undesirably
- undetermined
- undid
- undies
- undifferentiated
- undignified
- undine
- undiplomatic
- undiplomatically
- undirected
- undiscriminating
- undisposed