ii7

ii7 denotes the supertonic seventh chord, built on the second scale degree of a key. It consists of a triad built on degree two plus a seventh above the root, yielding a four-note chord.

In major keys, the second scale degree forms a minor seventh chord: for example in C major, Dm7 (D–F–A–C). The chord functions as predominant harmony that typically resolves to V or I, and is a key component of the common II–V–I progression (Dm7–G7–C).

In minor keys, the diatonic second-degree seventh chord is usually half-diminished: iiø7. For example in A minor, Bø7 consists of B–D–F–A. This chord also functions as predominant, commonly moving to V (e.g., Bø7–E7–Am).

Jazz and popular music sometimes extend ii7 with added tensions (such as 9th or 11th) or reinterpret it in borrowed contexts. The symbol ii7 simply indicates a minor seventh on the supertonic, while iiø7 indicates a half-diminished seventh in minor-key contexts.

Summary: The ii7 chord provides predominant function and a smooth route toward the dominant, reinforcing tonality through II–V–I progressions.