n.1 any marsh plant of the genus Lysimachia, esp. the golden or yellow loosestrife, L. vulgaris.
2 any plant of the genus Lythrum, esp. the purple loosestrife L. salicaria, with racemes of star-shaped purple flowers.
Etymology: LOOSE + STRIFE, taking the Gk name lusimakhion (f. Lusimakhos, its discoverer) as if directly f. luo undo + makhe battle