Swing

1. A rhythmic alteration to a straight beat creating a looser feel at approximately a 67% to 33% ratio between beats as opposed to a 50% to 50% ratio. Swing is most correctly notated as a quarter and eighth or eighth and sixteenth note combination in a triplet, but is often notated as a 75% to 25% dotted rhythm, and sometimes not at all, but suggested in descriptive text or interpreted by the performer. Originally derived from a swinging and swaying motion, such as of the arms, body, or a playground swing.
2. A style of music applied to Jazz, Rhythm and Blues, and Western genres, which has a "swing" feel. Most common use beyond "Western Swing" is applied to popular music performed by big bands from 1936 to around 1945, also known as the "Swing Era."