How do you play the C undefined/B chord?

To play the C undefined/B chord on piano, play the C undefined chord ( and undefined) with B as the lowest bass note. Place the B note below the other chord tones. Slash chords specify a particular bass note different from the chord root.

What notes are in the C undefined/B chord?

The C undefined/B chord uses the 0 notes of the C undefined chord — and undefined — with B played as the bass note in the lowest register.

What is a slash chord?

A slash chord (or compound chord) is written as Chord/Bass and specifies both a chord and a bass note. The note to the right of the slash is played as the lowest note. The C undefined/B chord means a C undefined chord with B in the bass.

C /B

The C undefined chord consists of the notes, with B as the bass note.

Piano keyboard showing the notes for a C undefined/B chord

How to play the C undefined/B chord

Play B as the lowest bass note in the left hand
Find C (Root) on the piano keyboard
Press the note to sound the C undefined/B chord