abbreviations
"Tr" - a traditional, usually academic definition or symbol
"Ex-" - example

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NA
see Vocentro

NATURAL HARMONICS
A section of Just Intonation dealing with the production of "partials" which accompany the fundamental tone when it is sounded. These partials do not play a significant role in the development of Harmony. They are however at the root of Timbre: the weaker they are, the more the sound is fluted and "dark"; the stronger they are, the more the sound is nasal and "bright".

NATURAL TUNING
see Short Branch Tuning and Long Branch Tuning

NEAPOLITAN SIXTH
An ANTE-1 chord, usually in the Chromatic Minor Mode, of major triad shape and sonority .

NI
see Vocentro

NINTH
Tr- Distance, in the Quantitative Dimension of Pitch (frequency) see Interval

NON-CHORDAL TONES
A Transformation in Harmony, in which a member of the chord is replaced (either permanently or temporarily) by a neighboring note.

NOTE-VALUES
Terms and symbols which define the relative duration of notes
      : the whole-note, the longest note-value in current use
      : the half-note, 1/2 of the whole-note
      : the quarter-note, 1/4 of the whole-note, 1/2 of the half-note
      : the eighth-note, 1/8 of the whole-note, 1/2 of the quarter-note
      : the sixteenth-note, 1/16 of the whole-note, 1/2 of the eighth-note
      : the thirty-second-note, 1/32 of the whole-note, 1/2 of the sixteenth-note...
A dot added after a note adds 50% to its duration (a dotted quarter-note = 3 eighth-notes, as in . = ).

NUCLEUS
The 3 principal chords (harmonic functions) of a mode - the TONIC, surrounded by the DOMINANT and the COUNTER(DOMINANT)