Black and Tann. pl. Black and Tans 1. A two-toned drink consisting of a layer of ale topped by a layer of stout.2. A member of a paramilitary force recruited in Britain and sent to Ireland as part of the Royal Irish Constabulary to suppress the Sinn Fein rebellion of 1919 to 1921.[Sense 2, from the colors of the original uniforms of the force, which combined khaki army trousers with dark-colored police jackets and caps due to lack of supply.]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.black and tan n (Brewing) a mixture of stout or porter and ale Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014Black? and Tan? n., pl. Black and Tans. a member of an armed force sent by the British government to Ireland in 1920 to suppress revolutionary activity: so called from the color of their uniforms. black?-and-tan? adj. (of a dog) being of a black color with tan markings above the eyes and on the muzzle, chest, legs, feet, and breech. [1855?60] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.