A group of nodes in a shared Ethernet network that compete with each other for access. Typically confined within a subnet, if two or more devices attempt to transmit at the exact same time, a collision will occur. In a switched Ethernet environment, each transmitting-receiving pair of nodes is essentially its own collision domain, except that no collision can occur because there is no sharing of bandwidth. See broadcast domain and CSMA/CD.
A physical region of a local area network (LAN) in which data collisions can occur. Collisions are most likely in LANs, such as Ethernets, that use non-deterministic medium access control (MAC) protocols such as carrier sense multiple access with collision detection (CSMA/CD). See also CSMA/CD, Ethernet, LAN, MAC, and non-deterministic.