/ Dictionary / Index A antiparallel: Meaning and Definition of Find definitions for: an•ti•par•al•lel Pronunciation: (an"tē-par'u-lel", an"tī-), [key] — adj. Math, Physics. (of two vectors) pointing in opposite directions. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: antiparallel (Thesaurus) antiparabema antiparticle Related Content Daily Word Quiz: ontiguous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language