root
The note a chord is built from and named after.
The note a chord is built from and named after: the C in a C chord. It is usually, though not always, the lowest note, and it anchors how the ear hears the whole stack. Move the root and you have a different chord.
Learn it: Triads
The one-sentence definition at the top is the same one the Theory Aide extension shows as a tooltip inside Ableton Live. Hover any dotted term for its own.