In Diogenes Laertius section on Democritus, one of Democritus' opinions is stated as:
The end of action is tranquillity, which is not identical with pleasure, as some by a false interpretation have understood, but a state in which the soul continues calm and strong, undisturbed by any fear or superstition or any other emotion. This he calls well-being and many other names.
Epicurus taught the reverse. Is there anything in the literature that posits that Epicurus was reacting against this particular doctrine of Democritus? Regardless, this seems like a good statement of what Epicurean pleasure is not.