It is controversial whether δ?ναμι? in Metaphysics Book Θ has two distinct senses, one of which is strict, called “power,” and the other is the “more useful sense,” called “potentiality.” This paper argues that there are indeed two senses of δ?ναμι? in Metaphysics Θ, refuting Michael Frede’s “unitarian interpretation.” Distinguished from power, potentiality is neither Aristotelian nature, nor possibility, nor capacity for being, but rather a way of being. This paper examines the ontological meanings and the features of potentiality as a way of being. Basically, potentiality has a dual status, that is, it is being, on the one hand, and not-being on the other. Furthermore, it has a teleological direction toward its correlative actuality, which explains how potentiality ontologically depends on actuality and why actuality is substantially prior to potentiality.