The E half-diminished seventh chord (abbreviated "Em7(b5) chord") is a four-note chord consisting of the notes E, G, B♭, and D. The chord is formed by lowering the fifth of a E minor seventh chord a half step.
E half-diminished seventh chord
E half-diminished chord E minor seventh flat five chord
E G B♭ D
1 ♭3 ♭5 ♭7
Eø Eø7 Em7b5 E–7(b5) Emi7(b5) Emin7(b5)
tetrad (four-note chord)