contact

Contact is a term with multiple related meanings. At its core, it denotes the state or act of touching or being in proximity between objects, people, or substances. In everyday language, contact often refers to communication, as in making contact with someone by phone, email, or in person, or to contact information—the address, phone numbers, and other details used to reach someone.

In physics and engineering, contact describes the physical interface where two bodies meet. Contact forces arise from deformation at the interface and produce phenomena such as friction, wear, and pressure distribution. Electrical contact refers to the conductive connection that allows current to flow between components, with concerns including contact resistance, wear, and arcing.

In medicine and biology, contact can indicate exposure to a substance or person, as in contact dermatitis, caused by skin contact with allergens or irritants. Contact tracing is a public health technique used to identify people who may have been exposed to an infectious disease.

In astronomy and space exploration, the term is used to describe a hypothetical or observed interaction between civilizations (first contact) or the point at which two celestial bodies touch, such as a contact binary star.

In everyday use, contact is often used to describe the presence of a channel for communication or the preservation of relationships, as well as the practical information needed to establish that connection.