Terms not explained elsewhere but useful to know

Summary of terms in alphabetical order.

Two chords or scales in Twelve Tone Equal Temperament that share the same pitch classes are said to be equivalent. This holds true for the chords Dm7(b5) and Fm6 or the scales C.natural-minor and G.phrygian, for instance. Equivalent chords or scales are not necessarily identical.
The first note of a scale or chord that also starts its name.
The distance between two pitches measured in halftones.
Interval Structure
The pattern of intervals that identify a chord or scale, independent of a root pitch. The interval structure of Am9 is thus m9, and the structure of F.harmonic-minor is harmonic minor.
The process of mapping all parameters to MIDI output.
The overall timbre and rhythmical experience evoked by multiple instruments interacting with each other.
Twelve Tone Equal Temperament
Also abbreviated as 12TET. Divides an octave into 12 equal halftone steps such that all 24 keys in the Circle Of Fifths share same pitches (frequencies) over all octaves. This allows for compositions to be transposed freely. Without 12TET, instruments need to be retuned for each key.