Definition of flatten
: to make flat: such as
a : to make level or smooth
b : to knock down also : to defeat decisively
c : to make dull or uninspired
—often used with out
d : to make lusterless
flatten paint
e : to stabilize especially at a lower level
: to become flat or flatter: such as
a : to become dull or spiritless
b : to extend in or into a flat position or form
c : to become uniform or stabilized often at a new lower level
—usually used with out
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Time Traveler for flatten
The first known use of flatten was in 1630
See more words from the same year