means A fragrant purple-flowered shrub of the mint family, prized for its calming scent and oils, and by extension the pale purple color of its blooms.

from From Medieval Latin 'lavandula,' likely tied to Latin 'lavare,' to wash — the herb was tossed into baths and laundry to perfume them, which is also why washerwomen were once called 'lavenders.' It reached English through Old French 'lavendre.' A neat coincidence reinforced the link: the color is lavender, yes, but the root keeps pointing back to the washtub.