water-rocket1
/ˈwɔːtəˌrɒkɪt/Now rare
noun
Any of various aquatic or semiaquatic plants of the genus Rorippa (family Brassicaceae (Cruciferae)), as creeping yellowcress, R. sylvestris, and common yellowcress, R. palustris.
Origin
Early 17th century. From water + rocket, probably after post-classical Latin eruca aquatica.
water-rocket2
/ˈwɔːtəˌrɒkɪt/noun
1A firework designed to be discharged in the water. Now historical.
2A model rocket consisting of a hollow vessel that is partially filled with water and launched by pumping air (or some other gas) into it until the resulting pressure forces the water out of a nozzle, propelling the rocket upwards.
Origin
Mid 17th century; earliest use found in John Bate (fl. 1626–1635), writer on mechanics. From water + rocket.