<p><strong>Noun</strong></p><ul><li>(Sometimes initial capital letter) Classical Mythology: any of a class of nymphs presiding over rivers and springs.</li><li>The juvenile form of the dragonfly, damselfly, or mayfly.</li><li>A female swimmer, especially an expert one.</li><li>Botany: a plant of the genus Najas, having narrow leaves and solitary flowers.</li><li>Entomology: an aquatic nymph.</li><li>A freshwater mussel.</li></ul>