to stop supporting someone, or to leave someone without any support or purpose

The company was absorbed into a large conglomerate and most of its employees cast adrift. 这家公司被一家大型企业集团并购，而其大部分员工遭到遣散。

While the government does not have the power to remove him, the damaging claims may persuade them to cast him adrift. 虽然政府无权罢免他，但这些破坏性的指控可能会促使其收回对他的支持。

to leave something such as a small boat, or the people in it, moving on water without being controlled by anyone

They plotted to get rid of the Duke by casting him adrift on the ocean in a tiny boat. 为了除掉公爵，他们密谋将他丢在船上任其漂流。