Hexis is a Greek word, important in the philosophy of Aristotle. It stems from a verb related to possession, and Jacob Klein, for example, translates it as "possession". It is more typically translated in modern texts as "state" (e.g. Rackham) but "disposition" is perhaps the least controversial choice. Joe Sachs, who in the tradition of Klein tries to be as literal as possible, translates it as "active condition".
For the meaning of hexis and the related term diathesis, see Aristotle Categories viii, and Metaphysics V.xx.2.1022b, compared with V.xix.1022a. It becomes clear that what is important in being a hexis is having a stable arrangement of parts. Being static, as opposed to stable, does not seem to be mentioned. (Stasis, in Greek, was “rest”.) In fact, it would seem that neither a hexis nor a dunamis are static or moving because they do not exist in that way, whereas the argument of Metaphysics IX makes clear that what actually exists is something moving.
This type of distinction is often seen as a distinction between an activity and a fixed unchanging state, which is a distinction that makes some intuitive sense, because people tend to analyse causality in terms of idealized, but imaginary, states and changes in states. People think this way even though the possibility of a true state, or indeed anything at all which is unchanging is something highly problematic whenever one attempts to find a real equivalent to such beings. Indeed, the problem of whether there are any real unchanging beings was a major question behind much of Greek philosophy.