Astronomy •
Interplanetary medium, material that fills the Solar System •
Interstellar medium, the matter and energy between a galaxy's stars
Communication •
Media (communication), tools used to store and deliver information or data •
Medium of instruction, a language or other tool used to educate, train, or instruct
Wave physics •
Transmission medium, in physics and telecommunications, any material substance which can propagate waves or energy •
Active laser medium (also called gain medium or lasing medium), a quantum system that allows amplification of power (gain) of waves passing through (usually by stimulated emission) •
Optical medium, in physics, a material through which electromagnetic waves propagate •
Excitable medium, a non-linear dynamic system which has the capacity to propagate a wave
Other uses in science and technology •
Data storage medium, a storage container in computing •
Growth medium (or culture medium), in biotechnology, an object in which microorganisms or cells experience growth •
Porous medium, in engineering and earth sciences, a material that allows fluid to pass through it, such as sand ==Other uses==