The Collaborative International Dictionary of English v.0.48:

Terpsichore \Terp*sich"o*re\, n. [L., fr. Gr. ?; ? enjoyment
   (fr. ? to gladden) + ? dance, dancing.] (Gr. Myth.)
   The Muse who presided over the choral song and the dance,
   especially the latter.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Terpsichore
    n 1: (Greek mythology) the Muse of the dance and of choral song
    2: taking a series of rhythmical steps (and movements) in time
       to music [syn: dancing, dance, terpsichore,
       saltation]