The act, or the result of making something flat of flatter(noun)
A flattened part of something(noun)
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Use "flattening" in a sentence
"Success is defined as flattening the competition, not creating excellence."
"We do expect even though there might be a short-term flattening of use in certain areas even within label, there should be increased interest in K-ras characterization and considering ERBITUX when other therapies are failing."
"a property price correction was clearly under way, it was most likely to resemble the kind of long-term flattening of prices seen in the Sydney housing market after the effects of the first round of the first home buyer grant abated in 2003."