The story
- Latin · derived fromavis tarda“slow bird”
- Old French · derived frombistarde
- Middle English · inherited frombustarde
- English todaybustard
From Middle English bustarde, from an Anglo-Norman blend of Old French bistarde and oustarde, both from Latin avis tarda (“slow bird”), which is a misnomer as bustards are fast runners.
Etymology from Wiktionary, CC BY-SA 4.0.