It depends if you're describing a semantic model or you're concerned about implementation details.

Semantically, a goroutine is a thread, within a shared memory model. But what makes Go unique (or let's say more unique) is that it offers programmers a thread-like programming approach (linear, blocking code) but internally turns it into an event-driven approach (epoll/kqueue) for networking.

Moreover, the fact that goroutines are much cheaper than OS-level threads enable a more pervasive approach to concurrency.