/bat"wing'/ , adj.
1. formed, shaped, etc., in the manner of a bat's wing or wings.
2. (of a garment or part of a garment) resembling or conceived of as resembling the wing or wings of a bat, as a loose long sleeve (batwing sleeve) having a deep armhole and a tight wrist.
[ 1955-60; BAT 2 + WING ]