Pronunciation: (flat'n), [key]
1. to make flat.
2. to knock down: The boxer flattened his opponent in the second round.
1. to become flat.
2. flatten in, Naut.See flat 1 (def. 57).
3. flatten out, Aeron.to fly into a horizontal position, as after a dive.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.