autochthon

UK: /ɔːˈtɒkθən/ US: (ô tok′thən)

WordReference Random House Unabridged Dictionary of American English © 2025

au•toch•thon  (ô tok′thən), n., pl. -thons, -tho•nes 

(-thə nēz′). 
1. Anthropology an aboriginal inhabitant.
2. Ecology one of the indigenous animals or plants of a region.
3. Geology a geological formation formed in the region where found. Cf. allochthon.

• Greek autóchthōn of the land itself, equivalent. to auto- auto-¹ + chthó̄n the earth, land, ground
• 1640–50

Collins Concise English Dictionary © HarperCollins Publishers::

autochthon / ɔːˈtɒkθən -θɒn/ noun ( -thons, -thones / -θəˌniːz/)

1. (often plural) one of the earliest known inhabitants of any country
2. an animal or plant that is native to a particular region

Etymology: 17th Century: from Greek autokhthōn from the earth itself, from auto- + khthōn the earth