Texture - The interweaving of melody and harmony
Monophonic - one unaccompanied melody (also called Unison)
Homophonic - one melody with some type of accompaniment (most common texture)
Polyphonic - two or more melodies at the same time. May be with or without accompaniment. This is "the crowning achievement of Western Music".
Polyrhythm - more than one rhythm that occurs simultaneously. [we talked about this term as the "crowning achievement of African music"]

Musical Example: Handel's Messiah: "Hallelujah Chorus". Illustrates how texture may change at any given time in a musical work.

Harmony - The vertical relationship of combined notes - two or more pitches played at the same time - usually associated with accompanying a melody
Key/.Tonality - the idea of building a piece of music around a central or home sound. As I explain it, all the notes sound good together. This is what key is all about. 99% of what we hear regularly is in a key.
Consonance - stability. Pitch combinations that sound pleasant or stable
Dissonance - instability. Pitch combinations that sound unpleasant or unstable