burst·er (bûr?st?r)n.1. An offline device used to burst computer printouts.2. An astrophysical object that emits a brief but intense burst of gamma or x-radiation.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.