A period is a phrase consisting usually of an antecedent and consequent and totaling about 8 measures in length (though this varies depending on meter and tempo). Generally, the antecedent ends in a half cadence while the consequent ends in an authentic cadence. Frequently, the consequent strongly parallels the antecedent, even sharing most of the material save the final measures. In other cases, the consequent may differ greatly (for example, the period in the beginning of the second movement of the Pathetique sonata). In music a phrase (Greek φράση, sentence, expression, see also strophe) is a section of music that is relatively self contained and coherent over a medium time scale. ... In Western musical theory a cadence (Latin cadentia, a falling) is a particular series of intervals (a caesura) or chords that ends a phrase, section, or piece of music. ... In Western musical theory a cadence (Latin cadentia, a falling) is a particular series of intervals (a caesura) or chords that ends a phrase, section, or piece of music. ...

The 1958 Encyclopédie Fasquelle defines a period as follows:

• "A complex phrase, in which the various parts are enchained."

Another definition is as follows: In music a phrase (Greek φράση, sentence, expression, see also strophe) is a section of music that is relatively self contained and coherent over a medium time scale. ...

• "In traditional music...a group of measures comprising a natural division of the melody; usually regarded as comprising two or more contrasting or complementary phrases and ending with a cadence." (Harvard Dictionary of Music, 1969)

In musical notation, a bar or measure is a segment of time defined as a given number of beats of a given duration. ... Look up melody in Wiktionary, the free dictionary. ... In Western musical theory a cadence (Latin cadentia, a falling) is a particular series of intervals or chords that ends a phrase, section, or piece of music. ...

Source

• Nattiez, Jean-Jacques (1990). Music and Discourse: Toward a Semiology of Music (Musicologie générale et sémiologue, 1987). Translated by Carolyn Abbate (1990). ISBN 0-691-02714-5.
  • (1969). Harvard Dictionary of Music.