standard
A published specification, kept by a standards body, that many vendors build to.
A standard is a specification maintained by a standards body (IEEE, the Bluetooth SIG, OASIS, the IETF) that independent products implement so they can work together.
Examples
IEEE 802.11 (Wi-Fi) is a standard from the IEEE; the Bluetooth Core Specification comes from the Bluetooth SIG.
MQTT 3.1.1 and 5.0 are OASIS standards that many brokers and client libraries are built to.
See also