/ Dictionary / Index A allochthonous: Meaning and Definition of Find definitions for: al•loch•tho•nous Pronunciation: (u-lok'thu-nus), [key] — adj. Geol. not formed in the region where found. Cf. autochthonous (def. 4). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: allochthonous (Thesaurus) allochthon allocution Related Content Daily Word Quiz: beseech Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language