IEEE Std. 211-2018 provides terms and definitions used in the context of electromagnetic wave propagation relating to the fields of telecommunications, sensing, astronomy, optical waves, plasma waves, the ionosphere, the magnetosphere, and magnetohydrodynamic, acoustic, and electrostatic waves. Some obsolete terms and definitions have been removed. The language used for some already existing terms have been refined. The standard also includes some additional terms that are commonly accepted in these fields. IEEE Std. 211-2018 is the 4th revision of the original IEEE Std. 211-1969, following those of 1977, 1990 and 1997. The revision has been coordinated with the IEEE Antennas and Propagation Standards Committee (APS/SC). An invitation is hereby extended to the users of this standard to contribute to the 5th revision whenever they see deficiencies or have ideas for improvement by communicating with the APS/SC Chair, Prof. Vikass Monebhurrun, via e-mail to This email address is being protected from spambots. You need JavaScript enabled to view it..