Ariya

The Buddha used the term ariya to refer to those who had achieved a direct experiential insight into the nature of the four truths (suffering, its origins, its cessation, and the way to its cessation).

For such people these truths are no longer beliefs or theories but realities. When someone comes to know them as such, he or she is said to have "entered the stream."

~Stephen Batchelor, in Secular Buddhism