[un.du.la.tion] n (1646) 1 a: a rising and falling in waves b: a wavelike motion to and fro in a fluid or elastic medium propagated continuously among its particles but with little or no permanent translation of the particles in the direction of the propagation: vibration
2: the pulsation caused by the vibrating together of two tones not quite in unison
3: a wavy appearance, outline, or form: waviness