To upset the balance, stability, or equilibrium of: "By being too good a singer, too hell-bent an actress, and too strong a presence, the star unbalances the proceedings” ( John Simon).
To derange (the mind).
The condition of being unbalanced.
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.