Field
A physical quantity that has a value in every point in space, e.g. temperature, pressure, or flow rate of a river. A field may vary in space – a torrent's flow changes when the riverbanks narrow or if there is a waterfall – and in time – in case of rising waters or drought. The concept of field is essential to describe the wave-related aspects of particle physics. The concept is also useful to study continuous media (macroscopic properties of solids, fluids, etc.).