The D minor ninth chord is a 5-note chord consisting of the notes D, F, A, C and E.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Dm9.
Chords that are a superset of Dm9. The chords include more notes but always D, F, A, C and E.
Chords that are a subset of Dm9. These contain less notes but all of them are included in Dm9.
In case you prefer a non-interactive variant of the chord chart, we've embedded a PNG image below that shows the notes for the the Dm9 chord. Feel free to save or share the image as needed.