This paper discusses some issues concerning the definition of moral virtue in Nicomachean Ethics 1106b 36- 1107a 2. It is reasonable to expect from a definition the complete enumeration of the relevant features of its definiendum, but the definition of moral virtue seems to fail in doing this task. One might be tempted to infer that this definition is intended by Aristotle as a mere preliminary account that should be replaced by a more precise one. The context of the argument (...) Aristotle develops in Book II of his NE give us some help. I argue that the definition of moral virtue, once considered in the light of its context, is far from being an incomplete and provisional account: it rather introduces coherently the same notion of moral virtue that Aristotle employs in other texts (as in Nicomachean Ethics VI 13). My main proposal is that the way in which "hexis" is understood in the context of previous chapters allows Aristotle to encode in it the notion of an ability to do the right things regularly. Thus, moral virtue is a "hexis prohairetike etc.", but the ability to do the right things regularly is already encoded in the occurrence of "hexis" in the definiens account of moral virtue, as if Aristotle meant "hexis [praktike] prohairetike". (shrink)