1:able to move
2:containing active properties <chemically~>
3:having energy or motivation
A young man was sitting in a reclining chair, contemplating the nuances of the universe, when a strange bit of linguistic pondering suddenly befell him: "I am sitting in this chair, yet I am still able to move. Am I ert?" The answer eluded him as he sat, his mind working feverishly on the problem. He thought, "If I had some sort of debilitating disease, I would be inert while in this chair, but alas I do not. I must be ert, I have to be."