History: What is the difference between harmonic and inharmonic waves?

What is the difference between harmonic and inharmonic waves?

• Inharmonics are integer multiples, harmonics are not.
  The opposite is true.
• Neither harmonics nor inharmonics are integer multiples of the fundamental.
  One is an integer multiple.
• Harmonics are integer multiples, inharmonics are not.
  Correct!
• Both harmonics and inharmonics are integer multiples of the fundamental.
  One is not an integer multiple.