The C dominant seventh flat five chord (abbreviated "C7(b5) chord") is a four-note chord consisting of the notes C, E, G♭, and B♭. The chord is formed by lowering the fifth of a C dominant seventh chord a half step.
C dominant seventh flat five chord
C E G♭ B♭
1 3 ♭5 ♭7
Tetrad (four-note chord)