hyacinth (n.) Look up hyacinth at Dictionary.com
1550s, "the plant hyacinth;" re-Greeked from earlier jacinth (late 14c.) "hyacinth; blue cornflower," earlier a precious stone blue (rarely red) in color (c.1200), from Old French jacinte and Medieval Latin jacintus, ultimately from Greek hyakinthos, probably ultimately from a non-Indo-European Mediterranean language. Used in ancient Greece of a blue gem, perhaps sapphire, and of a purple or deep red flower, but exactly which one is unknown (gladiolus, iris, and larkspur have been suggested). Fabled to have sprouted from the blood of Hyakinthos, youth beloved by Apollo and accidentally slain by him. The flower is said to have the letters "AI" or "AIAI" on its petals. The modern use in reference to a particular flowering plant genus is from 1570s.