Pronunciation: (aj'ur),[key] —n. 1. Also called double tide.Oceanog. a. a high tide in which the water rises to a certain level, recedes, then rises again.
b. a low tide in which the water recedes to a certain level, rises slightly, then recedes again.
2. (in ancient Roman building) an earthen mound or rampart, esp. one having no revetment.