A broad undulation of the open ocean, often as the result of a distant disturbance
A sudden growth of public feeling or support for something is often called a groundswell. There is undoubtedly a groundswell of support for the idea of a strong central authority The groundswell of opinion is in favour of a referendum. a sudden increase in a particular feeling among people groundswell of
{i} large sea waves before or after a storm; spreading, increase (of opinion or ideas)