from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A sequence of six tones with a semitone in the middle, the others being whole tones, that was used in medieval music.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A series of six tones denoted with the syllables ut-re-mi-fa-sol-la separated by seconds, the only of which that is a minor second being mi-fa.
from the GNU version of the Collaborative International Dictionary of English
- n. A series of six notes, with a semitone between the third and fourth, the other intervals being whole tones.
from The Century Dictionary and Cyclopedia
- n. In Greek music: A diatonic series of six tones.
- n. The interval of a major sixth.
- n. An instrument with six strings.
- n. In medieval music, a diatonic series of six tones, containing four whole steps and one half-step (between the third and fourth tones).
"hexachord" on which the present scale was perfected.
Of a similar nature is Ut queant laxis, for five voices, in which the tenor sings the isolated notes of the hexachord between snatches of four-voice polyphony.
Running longitudinally, there are four channels in it if it is a tetrachord; six, if it is a hexachord; eight, if it is an octachord.
It will be observed that this hymn provided syllables only for the six tones of the _hexachord_ then recognized; when the octave scale was adopted (early in the sixteenth century) the initial letters of the last line (s and i) were combined into a syllable for the seventh tone.
Just as in mediaeval times each hexachord commenced with _ut_, so now every octave of our tonal system commences with _do_.
Following out his system, he applied the newly acquired syllables to each of the hexachords -- for instance, the lowest hexachord, G A B C D E, which was called hard, became _ut re mi fa sol la_; the second, which was called natural, C D E F
For the fourth hexachord, which was called hard, this B was again raised a semitone.
Commencing with G, which was the lowest note of the system in Hucbald's time, the first hexachord was formed of G A B C D E; the second, following the example of the Greeks, he made to overlap the first, namely,
The next three hexachords were treated in the same manner; the last or seventh hexachord was merely a repetition of the first and the fourth.
In order to make this hexachord identical in structure with, the first and second, he flatted the B, thus making the succession of notes, F G A B [flat] C D.