Pan-Slav·ism (p?n-slä?v?z??m)n. A movement advocating the political and cultural union of Slavic nations and peoples.Pan-Slav?ic adj.Pan-Slav?ist n.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.Pan-Slavism n (Historical Terms) (esp in the 19th century) the movement for the union of the Slavic peoples, esp under the hegemony of tsarist Russia ?Pan-?Slavic adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014