The term allochthonous refers to an animal or plant species that for different reasons, such as anthropic or natural actions, is found to grow in a territory different from that in which it normally lives.
The term allochthonous (from the Greek ἄλλος (àllos) “other”, and χθών (chthòn) “soil / earth”) indicates the non-belonging of something or someone to the place of residence.
The term allochthonous can also refer to different sectors such as, in ethnology, where we mean a human being native to a place different from the place where he lives, and then takes on the meaning of a foreigner.
In geology, a tectonic unit that is located in a different place from the one in which it was formed is defined as allochthonous.
Finally, in paleontology, allochthonous refers to a fossil record unrelated to the paleo-environmental context in which it was found, and which therefore underwent active or passive (post-mortem) transport processes. The allochthonous term is in some ways the opposite of autochthonous.