ETYMOLOGY
from swag (to move heavily from side to side or up and down) + buttock
EXAMPLE
“… Mag. Look you heare then.
Fra. O see, see — dat is de gross english Douck, for
de swagbuttock’d-wife of de Pesant.
Mag. How like you this then? There’s a Reverence
I warrant you. …”
From: Five new playes, (viz.) The Madd Couple Well matcht. Novella. Court begger. City witt. Damoiselle
The Damoiselle, Or The New Ordinary
By Richard Brome, 1653
Lexicophilia 