flatten.

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.

To press one's body tightly against a surface, such as a wall or floor, especially in order to avoid being seen or harmed.

To knock down or lay low.

The prize fighter quickly flattened his challenger.

To become flat or flatter; to plateau.

Prices have flattened out.

To be knocked down or laid low.

To lower by a semitone.

To make vapid or insipid; to render stale.

To reduce (a data structure) to one that has fewer dimensions, e.g. a 2×2 array into a list of four elements.

To combine (separate layers) into a single image.