CmMaj11 is C, Eb, 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 CmM11 or Cm(maj11).

Root, 3rd and 7th. The 3rd and 7th set the quality; the 5th adds nothing, so it goes. That frees a string for a tension.
How you get to it. The turn that lands on CmMaj11 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 CmMaj11 and adds flat thirteenth.
Contains CmMaj11 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.