Spin-density wave (SDW) is a term used in condensed matter physics to describe a specific type of magnetic ordering in certain materials. It arises from the interaction between localized magnetic moments and the surrounding electron cloud, leading to a periodic modulation of the spin density. Some other words that can be used as synonyms for SDW include spin spiral, spin helix, and spin modulation. These terms refer to the same physical phenomenon of SDW but are used in different contexts or can describe different types of SDW ordering. No matter what term is used, SDW remains an intriguing phenomenon with many fascinating properties and potential applications in various fields of science and technology.