flatten

Verb

flatten (third-person singular simple present flattens, present participle flattening, simple past and past participle flattened)

1. (transitive) To make something flat or flatter.
   • As there was a lot of damage, we chose the heavy roller to flatten the pitch.
   • Mary would flatten the dough before rolling it into pretzels.
2. (reflexive) To press one's body tightly against a surface, such as a wall or floor, especially in order to avoid being seen or harmed.
   • With a bolt of fright he remembered that there was no bathroom in the Hob-house Room. He leapt along the corridor in a panic, stopping by the long-case clock at the end where he flattened himself against the wall.1994, Stephen Fry, chapter 2, in The Hippopotamus
3. (transitive) To knock down or lay low.
   • The prize fighter quickly flattened his challenger.
4. (intransitive) To become flat or flatter; to plateau.
   • Prices have flattened out.
5. (intransitive) To be knocked down or laid low.
6. To lower by a semitone.
7. To make vapid or insipid; to render stale.
8. (transitive) To reduce (a data structure) to one that has fewer dimensions, e.g. a 2×2 array into a list of four elements.
9. (transitive) To combine (separate layers) into a single image.