The term that defines species introduced to an ecosystem by humans is introduced species, also known as non-native species or exotic species.

Here are some other related terms:

* Invasive species: Introduced species that cause harm to the environment, economy, or human health.

* Alien species: A broader term that includes any species that is not native to a particular area, including those that have been introduced by natural means.

It's important to note that not all introduced species become invasive. Some may coexist peacefully with native species, while others may even benefit the ecosystem. However, it's always important to be aware of the potential risks associated with introducing new species to an environment.