Abmaj11 is Ab, C, Eb, G, Bb and Db. Its natural is the same note name as the 4th, while the major 3rd remains.
In a close voicing, sits one fret above . A sharp 11th raises that note one more fret; Abmaj11 calls for the natural 11th.
Let both notes sound only when you want that close interval heard. For the sharp 11th instead, played without a 5th, the chord is .
Also written AbM11, AbΔ11 or Ab major 11.

How you get to it. The turn that lands on Abmaj11 is to — the ii and the V of Ab — and shares its third and seventh with , so the hand barely moves between them.
Hear it land:→→
In which keys. Every note of Abmaj11 belongs to F minor (the ♭III) and Ab major (the I, the tonic).
Contains Abmaj11 and adds thirteenth.
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.