/ Dictionary / Index H hyperplane: Meaning and Definition of Find definitions for: hy•per•plane Pronunciation: (hī'pur-plān", hī"pur-plān'), [key] — n. Math. a subspace of a vector space that has dimension one less than the dimension of the vector space. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. hyperpituitarism hyperplasia 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