Hard swing

In jazz and related musical styles, the term swing is used to describe the sense of propulsive rhythmic "feel" or "groove" created by the musical interaction between the performers, especially when the music creates a "visceral response" such as feet-tapping or head-nodding (see pulse). The term "swing" is also used to refer to several other related jazz concepts including the swing note (a "lilting" rhythm of unequal notes) and the genre of swing, a jazz style which originated in the late 1920s.

As swing jazz was dance music and coevolved together with swing dances such as the Lindy Hop, the term swing can be understood as music that makes the listener want to dance. Even though there is overlap between these concepts, music from any era of jazz or even from non-jazz music can be said to have "swing" (in the sense of having a strong rhythmic groove or feel).

While some jazz musicians have called the concept of "swing" a subjective and elusive notion, they acknowledge that the concept is well-understood by experienced jazz musicians at a practical, intuitive level. Jazz players refer to "swing" as the sense that a jam session or live performance is really "cooking" or "in the pocket".

If a jazz musician states that an ensemble performance is "really swinging", this suggests that the performers are playing with a special degree of rhythmic coherence and "feel". Although referring to a "sense of swing" is often done in the context of ensemble performances (e.g. a jazz combo or band), even an unaccompanied soloist can be said to be performing with "swing".

Like the term "groove", which is used to describe a cohesive rhythmic "feel" in a funk or rock context, the concept of "swing" can be hard to define. Indeed, some dictionaries use the terms as synonyms: "Groovy ... [d]enotes music that really swings." The Jazz in America glossary defines it as "when an individual player or ensemble performs in such a rhythmically coordinated way as to command a visceral response from the listener (to cause feet to tap and heads to nod); an irresistible gravitational buoyancy that defies mere verbal definition."

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Wikipedia