The Collaborative International Dictionary of English v.0.48:
Two-step \Two"-step`\, n. A kind of round dance in march or polka time; also, a piece of music for this dance. [U. S.] [Webster 1913 Suppl.]WordNet (r) 3.0 (2006):
two-step n 1: a ballroom dance in duple meter; marked by sliding steps v 1: dance the two-step