mode, in grammar: see mood.

mode, in music. 1 A grouping or arrangement of notes in a scale with respect to a most important note (in the pretonal modes of Western music, this note is called the final or finalis), and the patterns of larger and smaller steps (in Western music, whole and half steps) which these notes form. In the Middle Ages eight modes were developed as a theoretical foundation for plainsong performance, notation, and composition. These modes, derived from church practice, and explained either in their own terms, or using terms drawn from ancient Greek music theory, were grouped in pairs, each pair containing an authentic mode and a plagal mode, which are distinguished by the difference in the position of their ranges with respect to the final. The range of each mode was an octave. The "authentic" mode has its final at the bottom (and top) of its octave, the "plagal" mode ranges from the fourth below the final to the fifth above it. Although Greek names came to be used for these modes—Dorian, Phrygian, Lydian, mixolydian, hypophrygian, etc.—there is no proof of direct relation to Greek theory. These eight modes were the basis for 11 centuries of musical composition. Freely treated, they have reappeared in the works of some 20th-century composers such as Vaughan Williams. In the late Middle Ages and during the Renaissance certain other modes were adopted, and in 1547 the Swiss theorist Glareanus described 12 as useful for composition. In the late 16th cent. and early 17th cent. the series was condensed in the major and minor modes in use today. The use of medieval modes by later composers is called modality in contrast to tonality. An extension of the term mode allows its application to the tonal systems of Hindu music, Arabian music, and Byzantine music.

2 In the 13th cent., six characteristic rhythmical patterns of long and short notes in ternary meter. Greek names—e.g., trochaic and iambic—were applied to these rhythmic patterns at a fairly late date, but there is no evidence of derivation from the meters of Greek poetry. These rhythmic modes governed composition until they were finally dissolved in the 14th cent. by Philippe de Vitry in his treatise Ars nova (see musical notation).

3 In 20th-century music, the various forms of the tone row in twelve-tone composition (see serial music). The row, an arbitrary arrangement of the 12 chromatic tones of Western music, can be used in four different forms: the original row, the original row reversed (from the last note back to the first note), the original row inverted (upside down), and the inversion reversed. Each of these is a mode.

mode, in statistics, an infrequently used type of average. In a group of numbers the mode is the number occurring most frequently. In the group 1, 4, 5, 5, 6, 6, 6, 6, 9, 9, the mode is 6 because it occurs four times and the others only once or twice.

In music, any of a variety of concepts used to classify scales and melodies. In Western music, the term is particularly used for the medieval church modes. Keys in tonal music are normally said to be in either major or minor mode, depending particularly on the third degree of the scale. The concept of mode may involve much more than simply a classification of scales, extending to embrace an entire vocabulary of melodic formulas and perhaps other aspects of music that traditionally occur in tandem with a given set of formulas. The term mode has also been used for purely rhythmic patterns such as those of the Ars Antiqua, which were based on ancient Greek poetic metres.

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In music, any one of eight scalar modes employed for medieval liturgical melodies. The modal system was conceived for the purpose of codifying plainchant (see Gregorian chant); the names of the modes were borrowed from the system used by the ancient Greeks, though the Greek system was inadequately understood and the connection between the two is illusory. The modes are distinguished according to the note used as the final (last note) and the emphasis placed on another note, called the dominant. The Dorian mode's final is D, the Phrygian mode's is E, the Lydian mode's is F, and the Mixolydian's is G. Each of these four original modes had a parallel mode (Hypodorian, Hypophrygian, Hypolydian, and Hypomixolydian) with a lower range. Though they principally employ the tones A-B-C-D-E-F-G, some replace B with B-flat. In the 16th century, further modes were identified—the Aeolian, on A, and the Ionian, on C (corresponding to modern minor and major). The mode on B was ignored because of B's problematic tonal relationship within the scale.

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