A largely level expanse of land at a high elevation; tableland.
"The hikers gazed out over the vast plateau, where snow-capped peaks surrounded their high-altitude campsite."
In plain English: A plateau is a flat, high area of land that looks like an island surrounded by mountains on all sides.
"The sales figures plateaued after reaching their peak last month."
Usage: Use the verb form plateaued or has plateaued rather than plateaused, as the latter is nonstandard. This term often describes temporary stability in growth, so avoid implying permanent stagnation when discussing trends.
To reach a stable level; to level off.
"After years of rapid growth, the company's sales finally plateaued at $5 million last year."
In plain English: To plateau means to stop growing or improving and stay at the same level for a while.
"His confidence plateaued after he failed to score in three games."
The word plateau comes from the French term plateau, which is a small or diminutive form of plat meaning "flat" or "plate." It entered English with this sense of a flat, elevated area, distinct from but related to the words plate and platter.