spicebush swallowtailn. A large swallowtail (Papilio troilus) of eastern North America having chiefly black forewings and bluish or greenish hindwings, the larvae of which feed on spicebush.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.