piano chord
Cm7♭5
C1E♭♭3G♭♭5B♭♭7
A diminished triad with a minor seventh rather than a diminished one — half diminished, and not the same chord as dim7.
What is true of it
Cm7♭5 is C, E♭, G♭ and B♭ — 1, b3, b5 and b7 counted from C.
These are also the notes of E♭m6/C and D♯m6/C. Which name is right depends on what is underneath and what came before — the notes alone do not decide.