voice
One continuous musical line in a texture, whether or not anyone is singing.
One continuous musical line within a texture, whether or not anyone sings it. A four-voice chord has four voices even on a synth, and tracking how each one moves is voice leading. Thinking in voices is what separates counterpoint from stamping chords.
Learn it: Voices
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.