An object is a philosophy term often used in contrast to the term subject. A subject is an observer and an object is a thing observed. For modern philosophers like Descartes, consciousness is a state of cognition that includes the subject - which can never be doubted as only it can be the one who doubts - and some object that may be considered as not having real or full existence or value independent of the subject who observes it. Metaphysical frameworks also differ in whether they consider objects existing independently of their properties and, if so, in what way. The pragmatist Charles S. Peirce defines the broad notion of an object as anything that we can think or talk about. In a general sense it is any entity: the pyramids, Alpha Centauri, the number seven, a disbelief in predestination or the fear of cats. In a strict sense it refers to any definite being. A related notion is objecthood. Objecthood is the state of being an object. One approach to defining it is in terms of objects properties and relations. Descriptions of all bodies, minds, and persons must be in terms of their properties and relations. The philosophical question of the nature of objecthood concerns how objects are related to their properties and relations. For example, it seems that the only way to describe an apple is by describing its properties and how it is related to other things. Its properties may include its redness, its size, and its composition, while its relations may include "on the table", "in the room" and "being bigger than other apples". The notion of an object must address two problems: the change problems and the problems of substances. Two leading theories about objecthood are substance theory, wherein substances objects are distinct from their properties, and bundle theory, wherein objects are no more than bundles of their properties.
A hole is an opening, usually circular, in or through a particular medium, usually a solid body. Holes occur through natural and artificial processes, and may be useful for various purposes, or may represent a problem needing to be addressed in many fields of engineering. Depending on the material and the placement, a hole may be an indentation in a surface, or may pass completely through that surface. In engineering, a hole may be blind or through if it is partial or complete depth.