In musical terminology, a bar or measure is a segment of time defined as a given number of beats of a given duration. The word measure is heard more frequently in the U.S., while bar is used in other English-speaking countries, although musicians generally understand both usages.

A bar line is the line which lies between or separates bars. While many see bars and bar lines as arbitrary, others feel otherwise: "The bar line is much, much more than a mere accent, and I don't believe that it can be simulated by an accent, at least not in my music." - Igor Stravinsky (DeLone et. al. (Eds.), 1975, chap. 3).

A hypermeasure, large-scale or high-level measure, or measure-group is a metric unit in which, generally, each regular measure is one beat (actually hyperbeat) of a larger meter. Thus a beat is to a measure as a measure/hyperbeat is to a hypermeasure. Hypermeasures must be larger than a notated bar, perceived as a unit, consist of a pattern of strong and weak beats, and along with adjacent hypermeasures, which must be of the same length, create a sense of hypermeter. The term was coined by Edward T. Cone. (Stein 2005, p.18-19, 329)

References

• DeLone et. al. (Eds.) (1975). Aspects of Twentieth-Century Music. Englewood Cliffs, New Jersey: Prentice-Hall. ISBN 0130493465.
• Stein, Deborah (2005). Engaging Music: Essays in Music Analysis, Glossary. New York: Oxford University Press. ISBN 0195170105.