/ Dictionary / Index A autochthon: Meaning and Definition of Find definitions for: au•toch•thon Pronunciation: (ô-tok'thun), [key] — pl. -thons, -tho•nes an aboriginal inhabitant. one of the indigenous animals or plants of a region. a geological formation formed in the region where found. Cf. allochthon. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: autochthon (Thesaurus) autochrome autochthonous Related Content Daily Word Quiz: designate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language