Tone
a sound that has definite pitch.
Interval
The “distance” in pitch between two tones.
Octave
When tones are separated by the interval.
Range
the distance between the lowest and highest tones that a voice or instrument can produce.
Register
Part of the total range of an instrument or voice.
Pianissimo
very soft (pp)
Piano
soft (p)
Mezzo piano
moderately soft (mp)
Mezzo forte
moderately loud (mf)