Etymology
From Middle English *haguster, aguster, from Old English *agustre, from Proto-West Germanic *agustrā, *agistrā, variant of *agastrijā (“magpie, woodpecker”); related to West Frisian ekster (“magpie”), Dutch ekster (“magpie”), German Low German Heister, Häster (“magpie”), Swabian Ägerst (“magpie”). Compare also German Elster (“magpie”).