[ flat-n ]
/ ˈflæt n /

verb (used with object)

to make flat.
to knock down: The boxer flattened his opponent in the second round.

verb (used without object)

to become flat.

Verb Phrases

flatten in, Nautical. flat1(def 61).
flatten out, Aeronautics. to fly into a horizontal position, as after a dive.

Origin of flatten

First recorded in 1620–30; flat1 + -en1


flat·ten·er, noun o·ver·flat·ten, verb (used with object) un·flat·tened, adjective

Example sentences from the Web for flatten

British Dictionary definitions for flatten

/ (ˈflætən) /


(sometimes foll by out) to make or become flat or flatter
(tr) informal
  1. to knock down or injure; prostrate
  2. to crush or subduefailure will flatten his self-esteem
(tr) music to lower the pitch of (a note) by one chromatic semitone Usual US word: flat
(intr foll by out) to manoeuvre an aircraft into horizontal flight, esp after a dive

Derived forms of flatten

flattener, noun