An elevated, comparatively level expanse of land; a tableland.
A relatively stable level, period, or state: Mortgage rates declined, then reached a plateau.
To reach a stable level; level off: "The tension seemed to grow by degrees, then it plateaued” ( Tom Clancy).
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.