Is it ensure, insure, or assure?
tidal tid·al (tīd'l)
Resembling the tides; alternately rising and falling.
(in the LXX. called "Thorgal"), styled the "king of nations" (Gen.14:1-9). Mentioned as Tudkhula on Arioch's brick (see facing page 139). _Goyyim_, translated "nations," is the country called Gutium, east of Tigris and north of Elam.