Chord

The noun chord is a musical term that denotes a group of three or more notes sounded together. It is also used in geometry to denote a geometric line segment in a circle.

Examples:
  • One chord is fine. Two chords are pushing it. Three chords and you're into jazz. (Lou Reed)
  • I love the chord sequences in classical music. I often use that sort of effect in my solos. (Jon Lord)

Cord

The noun cord refers to an electrical cable, a rope, or an anatomical structure (e.g., spinal cord, vocal cord).

Examples:
  • I invented the cordless extension cord. (Steven Wright)
  • My guitars are my umbilical cord. They're directly wired into my head. (Kirk Hammett)

A Quick Test