/ Dictionary / Index E Einstein: Meaning and Definition of Find definitions for: Ein•stein Pronunciation: (īn'stīn Ger. īn'shtīn&sec), [key] — n. 1879–1955, German physicist, U.S. citizen from 1940: formulator of the theory of relativity; Nobel prize 1921. 1880–1952, German musicologist in U.S. (l.c.)a unit of radiant energy, equal to the energy of radiation that is capable of photochemically changing one mol of a photosensitive substance. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: einstein (Thesaurus) einkorn Einstein equation Related Content Daily Word Quiz: cetacean Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language