While doing some random thinking, it has occurred to me that I can't think of an actual concrete concept of enlightenment in the Theravada tradition. As a matter of fact, with most of the literature from the Theravada tradition, the term "enlightenment" is rarely used (at least in my experience). I find the term used much more often in the Mahayana schools.
And yet, the basic story of the life of the Buddha remains the same for all traditions, each one talking about the Buddha attaining enlightenment as if it was a single event in time that happened in a flash of realization. The Theravada clearly takes the "gradual" stance on this issue, I suppose.
Is there a concept of sudden enlightenment or realization in Theravada? If so, how does this fit in with the Buddha's gradual path approach? If not, from where does the Mahayana derive this concept?

Dhammakid