 Possible objects—possibilia (sing. possibile)—are objects that are possible. What it is to be an object—which is a basic and universal metaphysical category—will not be discussed but will be simply assumed as understood. What it is to be possible is the focus. Possibility of an object should be understood in tandem with another notion, namely, actuality. The two notions are related at least in the following way: (i) every actual object is a possible object. A more controversial relation between the two notions is expressed as follows: (ii) not every possible object is an actual object, that is, some possible object is a non-actual object.