A dominant ninth chord is composed using a root/1st, major 3rd, perfect 5th, minor 7th and major 9th (or R/1-3-5-♭7-9) intervals played simultaneously. Generally written as C9 or Cdom9, it is good practice to simply use an uppercase C followed by a super scripted 9 to represent it in writing (ie: C9) however it is also common to see it written as Cdom9.
Dominant ninth chord profile
|Intervals||root/1st, major 3rd, perfect 5th, minor 7th, major 9th or R/1-3-5-♭7-9|
|Stability||Somewhat dissonant, resolved|
|Common names (examples in C)||C9, Cdom9, C7(add9)|
|C Dominant ninth chord voicing #2|