<p><strong>Noun</strong></p><ul><li>Any of various plants belonging to the genus <em>Lysimachia</em>, of the primrose family, having clusters of usually yellow flowers, as <em>L. vulgaris</em> (garden loosestrife) or <em>L. quadrifolia</em> (whorled loosestrife).</li><li>Any of several plants belonging to the genus <em>Lythrum</em>, of the loosestrife family.</li></ul>