Unicast

In computer network protocols, a unicast message, whether it be an application message, a routed packet, or an Ethernet frame, is unicast if the destination address is that of a single unique destination.

This contrasts with multicast, where the address maps to more than one destination (e.g., all people in sales).

Anycast is a specialized case of unicast, in that there is a single destination, but more than one devices can provide the identical service if they are reached, and the source will not know which of the devices actually responded.