fes·tal (f?s?t?l)adj. Of, relating to, or of the nature of a feast or festival; festive.[Middle English, from Old French, from Late Latin f?st?lis, from Latin f?stum, feast; see feast.]fes?tal·ly adv.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.