flatten

verb

• To make something flat or flatter.

  "As there was a lot of damage, we chose the heavy roller to flatten the pitch."

• 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.