Playable, correctly spelled, and not how the chord is normally voiced. Right now this is the shapes that put a ninth, eleventh or thirteenth below the root.
Amaj9 is A, C#, E, G# and B — Amaj7 with the ninth stacked above it.
It sounds a maj7 with more air in it. The ninth argues with nothing here, so it works anywhere a maj7 does.
Tonic — an extended resting chord.

| A | C# | E | G# | B |
|---|---|---|---|---|
| 1 | 3 | 5 | 7 | 9 |
Also written AM9, AΔ9, Ama9 or A major 9. The same chord either way; which spelling you meet depends on who wrote the chart.
Five notes and four fingers, so something has to go. Keep C# and G# (they fix the quality) and B (what the symbol is about). Let E and A go, in that order — a perfect fifth says nothing the root has not, and in a band the bass has the root.
Play Amaj9 as a shell — root, third and seventh — and the spare string takes the #11 (D#) or the 13 (F#).
All 14 common shapes as fret numbers, lowest string first. Hover or tap one to see it drawn.
How you get to it. The turn that lands on Amaj9 is Bm7 to E7 — the ii and the V of A — and E7 shares its third and seventh with Bm7, so the hand barely moves between them.
In which keys. Every note of Amaj9 belongs to C# minor (the ♭VI), E major (the IV, the subdominant), F# minor (the ♭III) and A major (the I, the tonic).
Every note of Amaj9 is in A major and A lydian.
Each of those is a page: the scale across the neck, and the chords it harmonises into — which is where Amaj9 sits in it. Every scale.
Change one note of Amaj9 and you have Amaj7 (drop the ninth), Amaj11 (add the eleventh), Amaj13 (add the thirteenth), AmMaj9 (the major third becomes the minor third), Aadd9 (drop the major seventh) or A69 (the major seventh becomes the sixth).
Amaj9 is a major chord — root, major third, fifth. Major chords on every root.
The common shapes and the derived voicings come from different places, and both are explained in how this site is built.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.