means A whirligig is a spinning toy or any object that whirls and twirls, and by extension anything dizzyingly fast-changing or fickle.

from From Middle English 'whirlegigg,' a marriage of 'whirl' (to spin, likely from Old Norse 'hvirfla') and 'gig'—an old word for a spinning top or a flighty, frivolous thing. Put them together and you get a doubly-spinning word, a top atop a whirl, which feels exactly right.