an imaginary line around the Earth forming the great circle that is equidistant from the north and south poles; "the equator is the boundary between the northern and southern hemispheres"
a circle dividing a sphere or other surface into two usually equal and symmetrical parts
in constant agitation; "a seething flag-waving crowd filled the streets"; "a seething mass of maggots"; "lovers and madmen have such seething brains"- Shakespeare