piano chord
Dm7♭5
D1F♭3A♭♭5C♭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
Dm7♭5 is D, F, A♭ and C — 1, b3, b5 and b7 counted from D.
These are also the notes of Fm6/D. Which name is right depends on what is underneath and what came before — the notes alone do not decide.