es·ti·va·tion also aes·ti·va·tion (?s?t?-v??sh?n)n.1. Zoology A state of dormancy or torpor during a hot dry period.2. Botany The arrangement of the floral parts in a bud.3. The act of spending or passing the summer.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.estivation (?i?st??ve???n; ??s-) n1. (Botany) the usual US spelling of aestivation2. (Zoology) the usual US spelling of aestivationCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014es?ti?va?tion (??s t??ve? ??n) n. the act of estivating. [1615?25] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.es·ti·va·tion (?s?t?-v??sh?n) Zoology An inactive state resembling deep sleep, in which some animals living in hot climates, such as certain snails, pass the summer. Estivation protects these animals against the heat and dryness of the summer. Compare hibernation.The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.estivation, aestivationObsolete, summering; the taking of a summer holiday.See also: Recreationthe arrangement of petals in a flower before it opens; prefloration. Also aestivation.See also: Flowersthe practice of certain animals of sleeping throughout the summer. Cf. hibernation.See also: Zoology-Ologies & -Isms. Copyright 2008 The Gale Group, Inc. All rights reserved.