The New English Dictionary connects it with a Teutonic stem meaning "holy"; from which is derived the Lithuanian szwentas, and Lettish swats.
swats idly at a fly with his tail.
E The burrow swats idly at a fly with his tail.
Whenever Phebe hisses and swats and I yell, she runs and hides!
Whenever she comes near us humans, or onto our bed or near the food or the litter box or anywhere, he swats at her and starts chasing her.