A visit with a long-lost cousin might arouse emotions that run the gamut of joy, regret, sorrow, and excitement. A gamut is a full or complete range.
In the 16th century, the gamut was the lowest note on the musical scale. In music as well as life, the word has expanded to mean from high to low, or the whole range. The word is often associated with "run," as in "run the gamut from totally excited to so terrified you're quaking with fear." And if you've talked about every discussion point on your agenda, you've covered the gamut of issues that need discussing.