tonic
theoryTON-ik
The first and most important note of a scale, serving as the tonal centre of a key.
The tonic is the foundational pitch of a key — the note that feels like home, where musical phrases naturally resolve. In the key of C major, C is the tonic. The tonic chord (built on the first scale degree) provides the strongest sense of stability and resolution in tonal music. Musical tension is created by moving away from the tonic through the dominant and subdominant chords, and release comes from returning to it. The relationship between tonic and dominant is the most fundamental harmonic relationship in Western music. In a cadence, the movement from dominant to tonic (V–I) creates the strongest possible resolution. The tonic establishes the gravitational centre of a piece; without it, tonal music would have no sense of direction or arrival.
The word "tonic" comes from the Greek tonikos, meaning "of or relating to tension" — the tonic is the pitch toward which all other notes feel pulled.