euripus

noun2

1. •
   A strait; a narrow tract of water, where the tide or a current flows and reflows with violence, like the ancient firth of this name between Euboea and Boeotia.
2. •
   A flux and reflux.

   • They have ordained that the provision of this establishment might be as stable as the earth on which it stands , and should not fluctuate with the Euripus of funds and actions — 1790