Definition from Wiktionary, the free dictionary
- The colour of a hyacinth (either the gem or the flower); reddish-gold (chiefly with reference to hair).
- 1674, John Milton, Paradise Lost, Book IV, lines 300-303, 
- His fair large front and eye sublime declared / Absolute rule; and hyacinthine locks / Round from his parted forelock manly hung / Clustering, but not beneath his shoulders broad:
- 1990, Camille Paglia, Sexual Personae:
- The beautiful boy has flowing or richly textured hyacinthine hair, the only luxuriance in this chastity.
- 1674, John Milton, Paradise Lost, Book IV, lines 300-303,