The C#dim7 chord (diminished 7th): notes C# E G A#, degrees 1 – ♭3 – ♭5 – ♭♭7. Guitar shapes: x42323, x45353, 9-10-8-9-8-x, 9-10-11-9-11-9.
A chord is the root plus degrees above it, most often stacked in thirds. Major and minor differ only in the lower third: a major third (M3) sounds bright, a minor third (m3) sounds sad. Pick a chord and a root to see its degrees and intervals, and its shapes.
m — minor, M — major, P — perfect, A — augmented interval; the number is the degree count. m3 is 3 semitones, M3 is 4, P5 is 7
C# C#m C#5 C#7 C#m7 C#maj7 C#sus2 C#sus4 C#add9 C#6 C#m6 C#9 C#dim C#dim7 C#m7♭5 C#aug