C#mMaj11 is C#, E, G#, B#, D# and F#. It keeps every note of and adds the .
Keep the minor 3rd, major 7th, and 11th audible. On guitar, root and 5th can be left out to make room for those notes.
Also written C#mM11 or C#m(maj11).

C#mMaj11 in 2nd inversion puts G# in the bass instead of C#, the 5th of the chord. The notes are the same; what changes is what the bass line does, which is most of why you would reach for it — it lets the lowest voice move by step where the root would have jumped.
One of C#mMaj11’s 5 shapes does this:x-11-11-11-13-12
How you get to it. The turn that lands on C#mMaj11 is to : the ii and the V of C# minor, which is where a minor tonic is usually arrived at rather than simply begun on.
Hear it land:→→
Contains C#mMaj11 and adds flat thirteenth.
Contains C#mMaj11 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.