/ Dictionary / Index J Jurassic: Meaning and Definition of Find definitions for: Ju•ras•sic Pronunciation: ( joo-ras'ik), [key] — Geol. Geol. —adj. noting or pertaining to a period of the Mesozoic Epoch, occurring from 190 to 140 million years ago and characterized by an abundance of dinosaurs and the advent of birds and mammals. See table under —n. the Jurassic Period or System. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: jurassic (Thesaurus) Jura Mountains jurat Related Content Daily Word Quiz: panacea Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language