I was under the impression that "Blue Moon" refers to the second full moon in a single calendar month. Actually, the original usage followed a different convention based on the seasons. Usually, a season has three full moons, but when there are four, the third one is known as a Blue Moon. It's probably too late to revive the original meaning. The history of the Blue Moon is explained in the following article.
At last we have the "Maine rule" for Blue Moons: Seasonal Moon names are assigned near the spring equinox in accordance with the ecclesiastical rules for determining the dates of Easter and Lent. The beginnings of summer, fall, and winter are determined by the dynamical mean Sun. When a season contains four full Moons, the third is called a Blue Moon.
Why is the third full Moon identified as the extra one in a season with four? Because only then will the names of the other full Moons, such as the Moon Before Yule and the Moon After Yule, fall at the proper times relative to the solstices and equinoxes.
As Hiscock explained in the March issue, widespread adoption of the second-full-Moon-in-a-month definition followed its use on the popular radio program StarDate on January 31, 1980.