Pronunciation: (bat'wing"), [key]
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 (bat'wing sleeve') having a deep armhole and a tight wrist.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.