A grounded metal rod placed high on a structure to prevent damage by conducting lightning to the ground.
One that attracts and absorbs powerful, typically negative feelings and reactions, thereby diverting interest from other issues: "[His] business dealings have become a lightning rod for criticism” ( Walter Shapiro).
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.