/ Dictionary / Index P Paschen-Back effect: Meaning and Definition of Find definitions for: Pa'schen-Back' effect" Pronunciation: (pä'shun-bäk'), [key] — Physics. Physics. a splitting of spectral lines observed when the source of a radiation is subjected to a strong magnetic field, caused when the vectors associated with the spin and orbital angular momentum exhibit individual rather than common precession. Cf. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. paschal letter Paschen series Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language