“oooooooh finally a non-latin based word!” {Old me was precious, weren’t they :P}

Swarm, from old english swearm, comes from the proto-germanic *swarmaz,(see related swerm, svarm, swaram, schwarm, svarmr from danish, swedish, middle dutch, old high german, german, and old norse, respectivly)

Derived from the proto-indo-european root *swer-, meaning ‘to buzz/whisper’, originally used to indicate the presense of bees. T he current general form, “large, dense throng” is attested from early modern english (circa 15c)