plateau

Etymology

Borrowed from French plateau, diminutive of plat (“a plate”); see plate. Doublet of platter.

noun

1. A largely level expanse of land at a high elevation; tableland.
2. (of a varying quantity) A comparatively stable level after a period of increase.
   Childhood obesity, rising for more than two decades, appears to have hit a plateau, a potentially significant milestone in the battle against excessive weight gain among children. 2008-05-28, Tara Parker-Pope, “Hint of Hope as Child Obesity Rate Hits Plateau”, in The New York Times, →ISSN
3. (dated) An ornamental dish for the table; a tray or salver.
4. (sports, broadcasting) A notable level of attainment or achievement.
5. (drug slang) Any of several distinct, dose-dependent stages of a dextromethorphan trip.

verb

1. (intransitive) (of a varying quantity) To reach a stable level after a period of increase; to level off.