The six months between the Easter and Advent seasons are called Ordinary Time.
Since the great liturgical seasons of the first half of the year focus on the greatness of our salvation, from the coming of Christ to the sending of the Holy Spirit, Ordinary Time offers a season in which to reflect on the meaning of those events in our everyday lives.*
There in nothing ordinary about Ordinary Time at all. It makes dailiness, stability, fidelity, and constancy the marks of what it takes for Christians to be "Christian" the rest of the year.+
The color that marks the season is green, reminding us that we continue to grow with purpose.
+from The Liturgical Year by Joan Chittister