The term Stargate describes the entry point for the Earth Federation Space Warp system developed in the late 2460s. Elias Huer was presumably involved in their introduction, based on him piloting the first ship through a Stargate in 2464, with the short trip transporting him across Earth’s solar system. His mission a success, a system of Stargates is developed to link trading planets throughout the Earth Federation and beyond.
The Stargate, which is only visible when in use, consists of an equilateral diamond formed by four points linked by thin energy beams.
The use of the term Stargate predates the 1994 film of that name by Dean Devlin and Roland Emmerich, and the various TV shows that followed. (It may have been inspired by the use of the term in the 1960s film 2001.