The Collaborative International Dictionary of English v.0.48:
Ragtime \Rag"time`\, n. (Mus.) a rhythm with a regular accompaniment in two-four time and a melody characterized by syncopation, first recognized in many negro melodies; also a style of American music in this rhythm. [Webster 1913 Suppl. +PJC] RaguledWordNet (r) 3.0 (2006):
ragtime n 1: music with a syncopated melody (usually for the piano) [syn: ragtime, rag]