early 15c., "whirlpool, eddy," originally Scottish, of uncertain origin, perhaps related to dialectal Norwegian svirla or Dutch zwirrelen "to whirl." The meaning "whirling movement" is from 1818.
1510s (transitive), with an isolated instance from 14c.; from swirl (n.). Intransitive sense "form in eddies, whirl in eddies" is from 1755. Related: Swirled; swirling.