a·car·i·cide (?-k?r??-s?d?)n. A substance or agent that kills ticks and mites.[New Latin acarus, mite; see acarid + -cide.]a·car?i·cid?al (-s?d?l) adj.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.acaricide (??kær??sa?d) n (Pharmacology) any drug or formulation for killing acaridsCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014acaricidea substance or preparation for killing mites or ticks.See also: Infestation, Killing-Ologies & -Isms. Copyright 2008 The Gale Group, Inc. All rights reserved.