For a pitched instrument, in which all the overtones are harmonic partials, the numbering of overtones and harmonics will be off by one, because the fundamental is not an overtone. Thus you have: F = 1st harmonic = fundamental; 2F = 2nd harmonic = 1st overtone; 3F = 3rd harmonic = 2nd overtone, and so on... So in summary: More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.