/ Dictionary / Index H hyacinthin: Meaning and Definition of Find definitions for: hy•a•cin•thin Pronunciation: (hī"u-sin'thin), [key] — n. Chem. phenylacetaldehyde. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. hyacinth bean hyacinthine Related Content Daily Word Quiz: vertigo Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language